I actually agree with you, because I really didn’t agree with your premise that someone saying, “You’re so dressed up!” is a fact.
If this thread has shown anything, it has been that people’s interpretation of, “dressed up,” runs the gamut.
That’s kind of why I used the example I did - though, I suppose, “overweight,” is somewhat relative, too. But, at least it is more objectively measurable than, “dressed up.”
To your point, there is no point to such comments about appearances. But, that doesn’t mean people don’t make them.
And, yes, some of dh’s family members are catty. I agree with @DrGoogle123 that delivery makes a difference. I am a person who is big into, “tone” and “inflection.” Imagine the question, “Do you like anchovies or your pizza?” Think how two people could say that same sentence and with one you could hear enthusiasm for anchovies on pizza and with the other you could hear disdain for anchovies on pizza. Lots more to our communication than just the words we use.