About 5 years ago I had a client who used my toothbrush, he didn't ask or anything I just found out, I hated it. For probably a year on I always kept my toothbrush hidden outside of the bathroom. And then started keeping it in the bathroom again.
Then, I think about 6 months ago? I found a bit of brown on my toothbrush, I smelt it it was... his no.2. When I asked him on the phone about it he denied it was him at first, then I got it out of him it turned out he was having trouble trying to make his poo flush down... yeah, I know, unbelievable

I will never ever keep my toothbrush in the bathroom ever again!
Men who step outside of the bath the instant they turn the shower off. OMG! pick the towel up and mostly dry yourself INSIDE the bath! leaves water all over the floor when I go in there.
When they want a drink, and only end up having a sip or two. Like, really?!
Turning up uninvited.
Getting lost for directions. And also asking me to come down to bring them up to my apartment - when I'm in my lingerie, skimpy dress and high/stripper heels. No, just no. You can afford escort prices so you have at least 1 brain cell in there to follow simple instructions.
Other things as well but I best not type a book here.