I agree to a point about lighting has a role to looking better in a mirror.
Yesterday i was taking shower at my girlfriends house and her lights were dimmed and was night and i looked good in her mirror always have but noticed it with dim lights. So now the light theory isnt the only cause to looking better.
i also notice the gym has better mirrors in the cardio class room with the hardwood flooring. But again i might be just tripping lol
3 types of mirrors google says
Plane
Convex
Concave