For me its: Oh no, not a guardrail! - There is a cacher in my area who puts these tiny little containers (well camo'd) on guardrails next to busy roads. I hate searching around guardrails on busy roads.
Oh no, not a high-profile location! In front of a store, or in a bush next to a real busy intersection.
Oh no, not under a bench! I hate searching under the bench, and usually there is someone sitting on it when I get there...
Oh no, not zip tied to a pine tree! For some reason I hate these caches. They take a while to find, and all the while you're getting poked! Again, there is a cacher in my area who loves these hides.
-
As for playgrounds, I hate those too. There is this one cache near me that is in a playground. It's missing now, and goes missing a lot, probably from kids finding it. Fortunately, when I went to search for it, the park was empty...
Forgot to add that I hate caches under bridges!