I had a really lovely couple stay with me for a long weekend. I needed to put something in their room, but when I opened the door, I was hit by the most disgusting smell. It was the strongest odour of stinky feet that I have ever smelt. These guests were showering, but some people have medical problems that cause these things.
At school, our IT teacher had a problem with BO. When they built the new IT block, they actually put a shower next to his office because of this. He still smelt bad though. As kids, we obviously used to make jokes behind his back, but when I was a bit older and realised it was a medical condition, I felt bad about it.
Anyway, there was not much I could do about the stink from the guest. I never mentioned it, just aired the room and, obviously, everything was washed before the next guest came. However, they also left black marks on the brand new set of towels that I was never able to get out. I don't know what it was, but it looked like shoe polish. Could have been something else though.