Worst one I have had is a passenger decided to give themselves a manicure and a pedicure on the last 30min RPT sector I was flying. When I went to give the floor a vacuum at the end of a long day, I had the joy to find a full set of toe nails and a full set of fingernail clippings on the floor of one of the seats!!
Charming......
Plus I have had most of the "up north" experiences. Including a bloke who decided that he couldn't hold the sneeze in long enough to turn AWAY from my face when I was giving a briefing in a 210. Quite possibly the most "yuck" experience I have ever had. Amazingly I didn't get sick in the weeks following!!