If you go relatively frequently to a place where there are lots of people whom you get to see repeatedly there is a good chance someone somewhere has or had a crush on you.
It doesn't mean that the crush will be long lasting or that the person crushing on you will be your type, nor that they are obsessed with your or you are the only one they have a crush on. There are people who have a crush on multiple people at the same time. There are people who have a new crush every day or week.
The more attractive you are and the more people you are exposed to on a daily basis the more likely someone fancies you. If you drive to work, work with women or in a tiny office, don't go out, don't post much on social media publicly, who is going to find you?!
If you have an attractive personality or looks, and it can be just one thing like you are really kind or have very pretty eyes, someone could crush just for that one quality about you so you don't even have to be model level of hotness to have admirers.
I think the key giveaway to finding out if someone has a crush is if they treat you differently to others for no logical reason.
In the case of those who ignore you which can come across as hating you, you will find that when you talk to them they will seem nervously happy and they will go out of their way to help. If they are standoffish despite a crush on you, you don't want them anyway because they have a lot of emotional and social issues they need to work on and if they are otherwise confident but with you they are so closed off despite their crush on you then there is something about you that reminds them of a toxic relationship in their history so either way if you 'bring out the worst' in them or each other its not butterflies its your body sounding alarm bells,I think it's a trauma response maybe you look, sound or smell like someone they have unresolved issues with so don't worry about the ones who are too nervous nor about the crushes you were too nervous around that you closed off.. it was just a sign that you need to work on the issues you have be it fear of rejection or body image issues or attachment issues or inferiority complex.
A healthy crush feels good, you feel.excited not scared or worried around them, you feel.an inner peace not.stomach in knots.