RE: The Ghost in the Bestiary: The Pathfinder Monster That Doesn't Exist

An interesting issue with our group is that the most experienced player also has a virtually eidetic memory. If I use a "standard" monster (from any of the many 3.5 Monster Manuals and other sources), he'll know the stat block in it's entirety. Even if he doesn't mean to, it's hard for him not to act to take advantage of a monster's weaknesses.

So most of the monsters I use are either completely homebrewed, or re-skinned standard ones with just enough changed to throw him off - swapping energy types around for attacks & resistances, blending the attack methods of two similar monsters, or just completely changing the description, habitat and habits even if the stat block is very similar.