While I do know the hotel committee tries, much like everything here it all comes down to money and the company doesn't care if you are living in a crap hotel, so long as they can legally say you can rest there. We do get moved out of hotels when things get bad, it just takes forever.
If you didn't get the rest you needed because of something at a hotel, document it with video and pictures, crew care it, notify the hotel and then fatigue it.
If you can't sleep at night because of bugs, noises, fearful of the neighborhood etc, document it, crew care it, notify the hotel and then fatigue it. Notify OSHA and the local health department as well. Pretty sure they would be interested in knowing a local business has a bug infestation.
If you are not fit to fly because you are sick due to mold or other unsatisfactory condition, document it, crew care it, notify the hotel and call in sick/fatigue. Go one step further and pipeline it or notify the FAA.
Its time this company gets off its ass and they won't do it so long as we continue to tolerate it. I will say though, while it is easy to ***** and moan about the hotel committee or the hotels themselves, positive crew cares are equally, if not more, important. I know, when things are going well you don't feel like sending in a good word, but it does go a long way.
In the case of the syringe and drug paraphernalia I would have notified the local police as well.