Rob Thomas, stop messing with my brain!
For the record, I am on the LoVe Boat. I like Logan & Veronica together: the acting of JD & KB is superb, they have chemistry, dialogue is wonderful, both are complex, and, now that you mention it -- the hot kissing scenes.
Right now in fandom there seems to be battle lines being drawn (nothing so bad yet as those battles over who Buffy dated, thank God.) Some think that there is something wrong about Veronica now being all ga ga over someone she described as "every school has an obligatory psychotic jackass. He's ours." The battle is shown in the pilot: Logan is nasty to Veronica; Veronica plants a bong in his locker; Logan smashes up her car.
Some of the theories so far: Veronica has low self esteem; Logan has some ulterior motives; Rob Thomas is giving in to the fans and already ignoring continuity; Logan has changed; the relationship shows the complexity of the show & the characters.
My favorite theory so far is that yes, Logan was an OPJ but as the later episodes revealed he was still hurting from Lilly's murder and all his bad behavior was because of that.
But: I've got a theory...it could be bunnies...
Oops. Wrong show.
Rob Thomas is a author who has written books for the teen audience and is well aware of some of the devices used in teen books. One is having the narrator be unreliable (in part because they only see from their POV) at the start of the book, and eventually realizing that other people have their own perspective on things. As the narrator realizes that these multiple, valid, perspectives exist, including ones not her/his own, the narrator becomes more reliable.
So -- why do we think Logan is an OPJ?
Because Veronica told us so.
Maybe Logan isn't an OPJ -- maybe that's just the way Veronica saw him. And now, as she gets to know him and sees him more fully, she realizes: yes, he acted like a jackass. But that doesn't mean he is one. And whatever he thought of Veronica -- bitter? vengeful? nasty? -- he has realized, that's not her.