I'm going to vet my gf's male friends
What would drive you to vet her male friends?
Because I'm a very nice guy. I don't want her to expose herself to trouble with the guys.
I know you are trying to help your girlfriend out, but it sounds like you want to snoop on her personal life to an extreme degree, which is usually considered wrong.
You are jealous since I'm a good guy and you are an asshole.
You should allow your girlfriend to determine which of her guy friends is best for her. If you get involved, she might think your intentions are bad.