Well, they are legion. And homo assholeous frequently has an array of talents that makes one superficially interesting. Your first response may be due to his unexpected abruptness or talents that stimulate curiosity. Also, warranted genuine assholes often are socially skilled and glib and have a suite of behaviors that call attention to themselves. They are never dull and uninteresting. All the better to play you!
Of course, asshole behavior is not simply to remove your panties. They go in for rudeness, abrupt manners, risk taking, and other jarring behaviors. Hey, some people are making careers out of being the character in Risky Business, including dancing in tighty whities! Be mindful, though, is that this aspect of assholeness is not simply immaturity; but a concerted effort to defy conventions and manners.
It's not an absence of or incomplete socialization; but the candidate going out of way to be rude and ill-mannered.
It is tempting to view these miscreants as engaging in self-defeating behavior; however, when coupled with daring and glibness, they can sometimes dramatically achieve. Even to winning major elective offices (I'm naming no names; you furnish 'em).
And here's a point: there are some fields where being a bit of an asshole can confer an advantage: politics, business, acting or comedy, and so forth. And they take advantage of the implicit willingness to accept by others their antics. For some, it's just a phase; for others, it's an ingrained trait!
So what are features of these non-rara aves? They are flamboyant, narcissistic, insensitive to others, and sometimes abusive. Without the burden of a diagnosis, I'm referring to behaviors that might be similar to certain personality disorders; specifically the narcissistic personality disorder, the histrionic personality disorder, passive-aggressive behavior, and even possibly the antisocial personality disorder. They basically get a lot of mileage from being difficult.
If you become enamored with one, you are in for a lot of embarrassment and disappointment. Don't overestimate your talent at reforming one; it's probably a lost cause. Acting like an asshole is very reinforcing for him or her. And it's ingrained.