[PF] How to size up enemies?

[Arbane]

No, I don't mean casting Enlarge Person on them, I mean is there a way (preferrably non-magical) to get a general idea how tough a given opponent is before the fight starts?

[NightbringerGGZ]

Knowledge checks would work. Specifically a Monster Lore check. You just have to a bunch of different versions of Knowledge trained.

[Arbane]

Knowledge checks work for monsters, but is there a good way to guess at class levels & such?

[Extra Anchovies]

Ask your DM if you can port over the uses that Complete Adventurer introduced for Sense Motive; they do exactly what you're looking for and Sense Motive is kind of a weak skill in PF.

[Hand_of_Vecna]

I've never seen it applied, but theoretically local should work that way. I don't think knowledges sepecifically state that their blind to class levels.

Non-PF answer: Oriental Advetures new use of Sense Motive pg. 58.

[Da'Shain]

In one game I ran I actually made this a function of the Appraise skill, because I'd never seen any character, ever, take Appraise, and I wanted to incentivize it. The way I worked it was similar to Monster Lore checks: 10 + CR of monster will give you whether the creature is lower level, the same, or higher level than you. Beating it by 5 or more told you what class it was, if it had any class levels. Beating it by 10 or more told you precisely how many class levels it had.

It wasn't used that often, because people still preferred having the appropriate knowledge to get info on precisely how to kill things (and avoid being killed), but it did save the party a couple times from running into a fight that it would have lost terribly. Overall I'd call it a lukewarm success, if you want to talk to your DM about trying something like that.