I don't wear makeup at all, so I've never encountered this personally -- after all, people have never had the opportunity to compare me with and without makeup. However, I admit that fear of this happening is partially why I don't use it. I worry that if I look significantly better with makeup on and people get used to seeing that, I'll never be able to just skip the makeup one day without people noticing and thinking I look ill/tired/crappy in comparison.
I don't want to put that kind of obligation/pressure on myself, so I plan to continue avoiding it except for super special occasions.
For those of you who do wear makeup (or who regularly observe people wearing makeup), is this a legitimate concern or am I just being silly?