I remember one year we went to Mexico in January. Our first night the temps were in the upper 60s and we slept with the window open. No screens on the window and we had a couple mosquitoes buzz around our timeshare. Just a small annoyance.
The next morning I was talking with the guy we bought the timeshare from. Nice guy and we were catching up when I mentioned they needed to add screens to the windows. His mouth fell open and he gasped, "You had the window open!" Then he remembered we were from frozen Minnesota. (He was a Canadian) He relaxed and we went out separate ways.
All week long it was so fun seeing the locals walking around bundled up in n hoodies and sweatpants while us tourists were in shorts and tee-shirts.
Easy to tell who was who.