Wonder why @Pizzagirl ? Is it just historic or something more recent?
Again, this is just my observation but @NJSue is so right on this one. The longer I live in Europe, the more similar we all become and more diverse the landscape.
There was a period of time @ 5-7 years ago where it was very popular for middle age women to have a purple tint hair color and cut somewhat “Flock of Seagulls”. I am not sure if this was the style in the USA at the time? It was a hard to describe color but one you might see on a 13-15 year old in the US 
It was also the style to have colored hair streaks and ombre color for women of all ages.
Yes, good dental care is important to Americans and hygiene in general. Everything is tiny here from the toothpaste to the deodorant bottles. You can tell a European from an American by the size of the toiletries they carry and also the size of their suitcase.
The getting up early and eating early really is a country specific thing. Years ago we took a family vacation to a German resort in Southern Spain (did not know when we booked). I kid you not, the Germans had staked out all the chairs around the pool by 6:30 am with their towels. My spouse had gone on an early morning run and noticed. We rolled into the breakfast buffet around 9:00 am and the food was gone and they were closing…yes that was a memorable vacation! Everyone was in bed by 9:00 pm Conversely, we took another vacation to Spain a few years ago and stayed in a very nice family resort. We did not sleep the entire time as the British and Italian tourists partied 24 hours a day. The Americans were the quiet ones.
Many cultures in Europe are screamers or equally as loud as the average American. Yes, at a place like The Vatican people are quieter however I find people notice Americans because we speak American English. They are curious, not because of something we DO or the volume of our voice but because they are fascinated by our country!
Maybe this:
LOL @NoVADad99 - my son’s all-time favorite.
Couldn’t the French and the British get over all that by now?
Contrary to those up-thread, I believe the arrogant US tourist is alive and well. Maybe it’s less noticeable in more populous cities where U.S. tourists tend to go (we’ve rubbed off on them to some degree I suppose) but overall I think it’s as ‘bad’ as ever. You can tell from several of the comments. We only have to look in the mirror for examples. When in Rome…
Vive la difference!
The comments about the absence of ice in soft drinks made me chuckle. When I grew up in Europe many decades ago, the Coke commercials were all about an icy drink served on top of large ice cube! Getting ice for soft drinks is not hard in Paris although asking for glace might trigger a smile as it generally refers to something slightly different than ice cubes or crushed ice.
Europeans do use ice in their drinks except when it is not called for or if the drinks are served icy cold. Yet, you will not find the typical US scenes where teenagers are sipping on 64 or 72 oz drinks loaded with a pound of ice and later loudly chewing on the crushed ice with abandon. Such scenes are bound to shock Europeans tourists just as Americans are disappointed about not getting loads of ice in their Iced Tea.
I am not sure why Americans tend to believe that what is different abroad is wrong, and especially in countries that are known as the birth of everything epicurean. Why would anyone assume hat the French of the Belgian do not know how to serve and consume soft drinks when they are passionate about their food. On the other hand, “our” version of food is often nothing else than fast food or reheated and mass-produced junk. After all, Europeans might not prefer to see their drinks diluted with ice that might have a dubious and unhealthy origin!
It is all a matter of what one got used to. I still put mayonnaise on my fries!
In Europe, only young people wear sneakers. If you’re an adult and wear sportgear outside of a sports-related place, it’s an indication you’re trying to look like a thug (especially if your pant legs are rolled up inside soccer socks), or that you’re an American. 
Football jersey + sports pants + nike sneakers + baseball cap + mini-messenger bag = the French thug look.
http://www.nixamere.fr/wp-content/uploads/2014/04/Yannick-Costla-Mode-survet-casquette.gif
Dark-skinned young people who wear sneakers and sports clothes may get an uncomfortable look for no reason because of the “thug” association. 
Also, I rarely see white socks on adults.
Young people LOVE to wear American-brand clothing, especially college apparel or pseudo college apparel.
(For some reason, Franklin&Marshall seems to be very popular).
So it’d be difficult to distinguish between an Italian studying abroad in London, and an American student studying abroad in London, except for the white socks.
One exception: Americans in continental Europe are known for being “immature drinkers” (ie., they drink the way Europeans did when they were 15 and were discovering the experience). Continental European college students do get drunk but the American abandon seems to puzzle them (“they get drunk on BEER? But how much of it do they drink???”)
Overall, there’s a sense that being an adult means to dress “well” for outside the house - not necessarily chic, but not in sports clothes. However, business attire is not as strict as in the US, even for management - business casual is common outside of the top executives (who do dress with equal care on both sides of the Atlantic). On the other hand, I don’t know if they have casual Fridays.
So, dress comfortably with a scarf on top of your parka/coat and any shoes but sneakers, and you’re good.
Older men wear flannel hats/flat caps, not baseball caps.
http://www.causeur.fr/wp-content/uploads/2010/05/papy-boom.jpg
^^couldn’t agree more. Loved the food in France, Italy (to die for), and Germany. I will let go of my ice thing if they will let me stay. 
Perhaps, a parallel discussion could be about how to recognize Western European business people at a US airport!
I’d venture to say that a safe bet to recognize your client is to look for someone who is wearing an expensive blue blazer and grey pants, and who is in dire need of a fresh shampoo and carries a suitcase that is way too small for his planned stay.
I actually bought my daughter a fanny pack when she was going to study abroad in Europe for a semester. Not to wear when walking around town, but I had read an article suggesting it for trips to hostels. It was great for storing toiletries and transporting it to the bathroom, where counter space is sometimes lacking or looks less than clean.
I wonder why this is an issue. I don’t think we expect European tourists to dress like Americans when they come here.
I think that is not hot the point. The original point was about blending in with the locals when traveling outside the US, mostly for safety reasons.
Well, the most recent attack didn’t seem to be targeting Americans.
“In Europe, only young people wear sneakers. If you’re an adult and wear sportgear outside of a sports-related place, it’s an indication you’re trying to look like a thug (especially if your pant legs are rolled up inside soccer socks), or that you’re an American.”
I agree that in Europe only young people wear sneakers, so a middle-aged woman wearing sneakers will look like a tourist. (Of course, if her feet hurt from anything else, so be it!) Watch it on the thug reference - I was chastised recently on another thread that it has racist implications ;-( (I don’t believe it does, but whatever.)
The most recent attack didn’t target anyone in particular, it targeted a way of life, a concept. The fact there were young people from the entire world drinking and chatting at the cafés, or in the concert hall, didn’t matter at all to the terrorists. They were after - explicitely- concerts (music being pervert and evil, as per their statement), drinking, mixing up (men/women, etc).
It’s easier to dress like Americans for Europeans who visit, because it essentially means “wear comfortable clothes, or whatever you like”. 
It’s not good to be an “obvious” tourist, IMO, not necessarily because one might avoid a terrorist attack (I certainly agree the most recent Paris attacks weren’t targeting tourists) but because a) I don’t want to be the typical “ugly American tourist” who expects things just like the US and expects everyone to speak English and b) it just marks you as a target for being ripped off or for petty street crime, if nothing else.
I don’t like to be instantly picked out as an American because I don’t want people making instant assumptions about me. Assumptions about my knowledge, ideas, tastes and politics. This was particularly the case during certain White House administrations, when our government was largely hated worldwide, in Europe in particular.
As a New Englander of a certain type who has also spent a lot of time in Manhattan, I tend to dress in muted colors with a lot of black, almost always natural fibers, wear sweats only on camping trips, never wear clothes with writing on them, have never owned a piece of “spirit” apparel whether it be college or athletic team, don’t gesture broadly, don’t speak loudly in public, tend toward a greater formality than many Americans, and don’t wear sneakers all the time. And I don’t drink soda. In CC discussions, we are frequently denounced as “unfriendly.” In Europe, we fly under the radar. B-)
BTW, on my most recent trip to Europe, in which I was in France, Italy, Switzerland and Austria, and drove through bits of Germany and Slovenia, I noted that the McDonalds restaurants were jam-packed with Europeans at all times. Sad but true.
@Zeldie, I would suggest that anyone who is convinced of their own superiority on all matters and who thinks that “Americans always…” or “the French always…” is…foolish.
I’ve always dress in Europe the same as I do when I go into the city - where, by the way, lots of people wear scarves because you do a lot of walking and it helps keep you warm. I can also tell who are tourists from the US when in the city. They are the ones who look like a waiting room at the bus station.