Sometimes guys feel that if a girl is very attractive, she is stuck on herself, and only wants a trophy guy. Most guys would not want a relationship with someone so shallow, so yes, they are leery. Looks are a whole lot less important than being open, friendly, non-judgemental. Just as you want guys to give you a chance, in spite of your beauty, guys want a girl who will give them a chance.
I remember a girl who treated everyone she met as though they were the most important person. She would smile and listen and respond kindly. She fairly glowed, and she was the most popular girl in the class. It was a joy to see her interact with others. I am sure all the boys thought she was beautiful.