A friend of mine who can be very very illusional XD and who is still trying very hard to turn the whole Jefferson-is-a-psycho thing upside down, just told me the other day: "Hey, Max is DRUGGED. How can we be sure that what she hears him say is what he is REALLY saying?! See, that scene there when he's like "DON'T MOVE your head!" - Maybe he's really just saying: "Max, stay down, play along, this room is under surveillance, there is some creepy Hostel shit going on here, they are watching us. If you don't want both of us to die, PLEASE don't move or they'll instantly burst in here and kill us."

Ok, so I for my part thought there were a few hints; you just had to look at some of his pictures all over campus; some of them were rather explicit; also there is a photo taken by Jefferson in Victoria's room which looks like a weird bird, and the same shape appears in Nathan's drawing on Wells' computer.

However, there is one thing which I found utterly stupid. Surely he needed the Dark Room because he just couldn't hold these photo sessions at Blackwell Academy, we can all see that. But when he's in the Dark Room with Max he keeps on talking about how soon everyone is going to appreciate these photos for the true art they are, and all I could think of was: "Really? You are REALLY going to show these to the public? Wow, good luck with explaining yourself then, psycho!"

However, it can be argued that he feels safe in the Dark Room because no one can watch him and his actions there and that's why he lets down his mask there and does and says those stupid psycho things you would never expect of him normally.

As to the point of "Why not just pay someone for posing", this is explained by Jefferson himself when he says that most models lose their naivitée sooner or later. Whatever he's looking for in the girls he kidnaps, he obviously cannot get it from someone who would pose for him willingly. He's fond of that "doe-eyed" dazed look when the girls wake up in the Dark Room and even more is he into that scared look they show when they start to wake up and realize what is happening to them. Would he look for a normal model he would need to hire a really good actress to recreate this look, I guess. And then it would still be "acted" and not innocent and natural as he wants it to be. It's weird to get into his mind and try thinking like him; we can only guess what is really going on behind those glasses.

I think there was way too much going on in LiS already, so the devs were probably okay with just saying: "We're not going to do a psycho-analysis of Jefferson and his motives at this point. He's a manipulative psycho, that's all what counts. End of story."