Think of it as a litmus test: if the guy that you'd consider asking reacts weirdly or badly if you ask him out, he was probably kind of flaky in other ways as well.
(A certain rigid and old-fashioned set of ideas about gender being likely among them).
We'd commented on each others posts, so one day, I just said hello in private.
Later I felt like I'd chased him b/c he couldn't believe a female talked to him!
I rarely ask because I'm afraid they'll take it to mean, "I want to have sex with you in the broom closet in 10 minutes" and sometimes I'm really just interested in getting to know them better first. I never directly ask, and I am usually very good at making my feelings known.
That said, I appreciate men's assertion that women should be willing to make the first move once in awhile because it's not fair to ask men to bear the entire burden of insecurity. But the one or two times I've asked I've been shot down pretty badly, even when there is chemistry.
“Hey.” A fine way to greet a real life friend, a cold (yet sufficient) salutation for a politically conservative family member, or something to shout at a cab that’s driven through a wet garbage puddle, soaking your pants.