When my kids were little we visited my in-laws in Mexico. Unfortunately we picked up a horrible Norovirus-like illness on our first flight. Despite having packed two full extra outfits and 2 days worth of diapers for the baby she arrived in Mexico bare-bottomed, wrapped in nothing but my camisole. Everything else was so covered in filth it had to be thrown away. The same virus serially swept through our entire group- 3 families, 10 people. We would each be violently ill for 24-36 hours and spend another 12-24 weak as a kitten trying to recover. The illness seemed to have a 6-12 hour incubation period so there wasn’t a single day when we were all healthy. We still each managed to enjoy ourselves on the 3/4 of the trip where we weren’t in the bathroom so it wasn’t a total wash.
Our worst non-vacation was the lakeside rental donated by one of the VPs in a company auction. The description was idyllic so we happily bid and invited friends for our week of sun and fun. Thankfully I checked it our before we went. It was tiny, lightless, unsafe for children, infested by mice, and smelled strongly of mold. You couldn’t have paid me to stay there.