I've been told by a number of people, who actually made a concerted scientific effort at studying and categorizing that which turns them on, that it completely ruined sex for them after they'd done it for too long. I really don't see the point. Perhaps I'm being pointlessly negative (no pun intended), but, if I'm cuddling with a girl, and then I start to lightly tease beneath her arms, or along her ribs, or grab a foot... I don't want to stop, and ask----or ponder, on my own----"Now, was that a 7, or an 8?"
I just want to have fun, and make sure she has a good time. Analyzing it seems... well, creepy.