1 bad experience...
The Capital Hilton is usually my FAVORITE place to stay in DC. Clean, nice big rooms, excellent location, and even decent food (limited menu). But my last stay there was devastating.
I arrived, unpacked, and went in the bathroom to place my toiletries. I noticed pubic hairs in the shower, but washed them down - hair can sometimes be tricky. OK, fine.
Then I went downstairs to grab a late dinner. I came back upstairs and lifted the toilet lid -- to find not only feces residue in the toilet, but ON THE SEAT. Oh my. Beyond disgusting!
Housekeeping came and was mortified. She cleaned the toilet with bleach and apologized. 
As if this weren't bad enough, the next day, when I returned from work, there was MORE hair in the shower (it wasn't there when I left), no feces to be seen, but when I pulled back the bed covers there was a pubic hair in the bed!
Clearly, that particular housekeeper had better things to do this week, and the Capital Hilton and I suffered as a result. Disappointing to say the LEAST.