A puddle in the bed
I had the worst hotel experience ever. I got into the bed at night and promptly realized I was lying in a puddle. My room was switched, but needless to say, I didn't sleep well. When I checked out, the morning person accused me of lying and charged my credit card for the room. She even refused to clean my pajamas. After I had been given an unclean room with a bed soaked in someone else's urine!
I have never experienced anything like this before.