How do I know if a man is just using me/settling for me?

I have always been the ugly short chick in HS,MS and college and almost every man was borderline ashamed of even being seen with me in public.

Now those same types of men have hit the wall so hard that they look unrecognizable. Not only that,but many of them are divorced with at least one kid under the belt.

Those types of men I know are the first type of users, since they never wanted to be with me back in their prime, and now see me as a backup plan during their decline.

However even when the man hasn't hit the wall yet, I want to know what is his usual type of women physically. I just cannot stand the idea of being the girl who looks nothing like his usual type, because that would make it quite clear that I was just the "settled for"/placeholder to whom the man settles because his usual type is out of his league, or they are not available yet.