I've always made it a point to use bare walls or use hotels I did not frequent. In addition to objects in the background of your pictures you could easily be identified by people who know you personally by how much of your tattoos you show and jewelry that you would normally wear daily.  

We all try to keep our private life's private and for our safety this is something to always keep in the back of our heads. Thank you for bringing lite to this subject.

I crop out details that may be identifiable by neighboring or unsuspecting eyes. I have seen pics posted on ads that clearly show their incall location. Like Bird mentioned...Wall art, bed covering, and furnishing in a room are all details that they(the ones you don't want looking at your ads) look at when scanning ads. The majority of the ads that Bird is referring to are from BP.  Always be aware of your surroundings.