He's remarkably good at this stuff, so you might've missed this. But Nick displayed his extreme manipulative evilness with ol' Liz right here. Liz definitely banged Nick at Tanner and Jade's wedding, and when she gets out of the limo she doesn't mention it (the banging), and it seems like he maybe doesn't remember her. But wait: he does!
When they meet up later, and he admits that he remembers everything and had a great time, then manages to use her lack of giving him her phone number after the liaison as a reason to basically tell her he's upset with her, because that meant she snubbed him and she could've gotten his number from Jade and he hadn't heard from her, so she didn't try... despite this poor, foolish girl fighting all the way through a ridiculously long and tortuous tryout process and actually quitting her job or whatever the hell happens to come on this show.
But no, she didn't try, so he doesn't care; time to talk to another girl, quick, quick. Nick's gotten in there before, and there are 29 other women on which to burn off his temporary charm, and this is the perfect opportunity to keep this one at arm's length. And it turns out he's 6-2, so his arms are definitely long enough to keep her away, like when you're a cartoon and you put your hand on your silly rival's head and he swings and swings but can't punch you no matter what. And after all that, he gives her the very final rose, to make her sweat, and so he doesn't obviously look like a terrible dude. THAT is everything you need to know about Nick.