I'm very shy, like super, I-will-do-my-best-to-shrink-into-the-background shy. So if I have a crush on someone I normally won't tell them unless I'm about 85% sure it won't end horribly even if they say no because chances are I am/was friends with this person before I had feelings for them and would like to remain so. I'll get over the rejection (rather quickly if my history is anything to go by) but I understand that it can be uncomfortable for some people, so usually I just keep it to myself and the feelings will eventually fade.
Now, if someone for some odd reason has a crush on me or finds me attractive, I'm completely gobsmacked because, what? Why??? This is because I grew up having the mindset that, as a disabled person, I am somehow broken and unworthy and all that fun stuff drilled into me. I am slowly working through that, but it's still kind of an issue. So imagine my surprise when people tell me they like me. It has happened though and either, the feelings are reciprocated so we try a relationship, I turn them down gently, or neither of us say anything about it and/or peruse it (or in the case of a childhood friend and I, were too young to really do anything about it)