Any character concept in pathfinder that revolves around starting with a template.

Play a mermaid? Centaur? Dark elf?

Ok sure. I can handle your special snowflake crap because I like playing oddballs myself.

But whenever someone's idea revolvea around a half-dragon/half-fey/some other weird thing, half (insert non core race here) that purely follows some bizarre logic revolving around the "rule of cool" I get a headache.

Mostly because I started out as that idiot, not realizing how much that stuff can damage a campaign. Never mind agitating the other players who may have made more normal characters.

Acquiring things like that in the late game tends not to be as disruptive, but level 1 half dragons are almost as much of a pain in the rear as that one guy's justification about how "A kender paladin is totally a viable concept!"

Someone pass me the ibuprofen. I'm gonna need it.