I think it's fair to say that ALMOST ALL guys have SOME standards.
That said, beauty is in the eye of the beholder. Some guys fetishize what other guys might find unattractive, such as being overweight.
I personally wouldn't ever ask a random girl for just a BJ. If a random girl asked to give me a BJ, then, as long as she was not elderly or deformed and had a fairly nice face, I would consider it. That said, it might be just the novelty factor for me, since, like almost all guys, I'm not used to girls making the first move, let alone bluntly offering me sex acts.