Never noticed that Indians do this, but now that I think about it...
For some reason, my gym seems to have a mix of the gym rats wearing expensive shoes and workout cloths and the "I just bought a membership, and I already feel more in shape" type of people that wear jeans and other out of place clothes. I guess I hadn't noticed this specific bit until now.
The old guy with the work gloves for lifting is a bit humorous, though.
I always grin when I see people wearing hoodies indoors.
Really? That seems like a really odd thing to get amused by. It's cold outside, they wear a sweatshirt. Do you want them to take it off immediately upon entering a building?
I hope you are referring to having the hood up, but even that is an odd thing to be amused by.