Episode 18 of VM, which I discussed yesterday, opens with Veronica making out with Deputy Leo (whose reappearance near the end of season 3 is a much needed bright spot) before her front door. He wonders why he's never been invited in and wants, he says, "to get a really good, long look at your bedroom ceiling."
"Wow! College girls must be easy," she replies.
The focus of the scene is the talking, not the kissing. There's no dramatic music, nothing unusual in the camera shot. You understand, from everything in the scene itself, that these two people like each other, but you also understand that Leo likes Veronica a lot more than she likes him. I thought Deputy Leo was a great character and was sorry Veronica wasn't nicer to him. But the show doesn't intend for them to have incredible chemistry, and they don't. The show does intend for Veronica and Duncan to have incredible chemistry, and they still don't.
The show intends for Veronica and Logan to have incredible chemistry, and they do. And it makes sense that they do. Because as they work together on things like finding out who stole the money at the poker game, what's going on with the various witnesses who claim to have seen Lynn Echolls jump off the bridge or ride away in a van, who is using the credit cards of Logan's supposedly dead mother, they come to see one another's virtues and vulnerabilities.
The kiss signifies something complicated and wonderful: they've discovered they have an emotional connection. As they acknowledge this emotional connection, it allows for an embodied attraction. (I use that slightly odd phrase because I think it covers more than calling the attraction merely "physical," as opposed to some other sort, like "emotional" or "intellectual." Emotions and thoughts are not just emotional and intellectual, they are embodied, and can cause physiological changes, including alterations in blood pressure, pulse, expression, posture, digestion, etc; and embodiment includes things like the way we carry ourselves, what our voices sound like, and how we adorn or decorate our bodies.) Admitting and acting on that attraction allows their emotional connection to deepen. And lust is part of every aspect of the embodied attraction and connection.