What are some unusual, or hidden places you clean in your home?

Stupidly, I never thought to clean out my toothbrush holder in the past 4 months or so (it’s not clear, and I’ve always had clear ones, so I guess it just didn’t occur to me)—and well, when I went to clean it tonight, I almost threw up.

What are things that you clean every so often? What are you obsessive about cleaning?