I have had one guy who I've given back the difference between an hour (which he booked) and a half hour. He popped within about 5 mins and was just unable to get him hard again. I tried to chit chat a bit and asked what line of work he's in, and he said "I'm a drug dealer". I was like, oh fuck. Then he asked me if I wanted to buy any drugs  After a reasonable attempt at getting round two going, I could sense him getting more and more moody so I just said "Why don't we call it half an hour - you're obviously really tired today, here's your ?50 back, go get some rest!"

If I'd been in a hotel I might have stood my ground but this was at home and really didn't want anything kicking off.

LMAO. I once had one of these too! It ain't funny when it happens but made me laugh once he was gone.
He was such a cute preppy looking guy. He was done in 5 min of course and he opened his very fancy satchel and...dear lord he had all sorts of drugs in there! Literally a shop! And he wanted me to buy his stuff!!!! Putting it all on my bed and talking me through it what is what... so I said I feel so bad for making him pay the whole hour and shall we cut it down to 30 min. He said it was fine he didn't want his money back he had to rush deliver some clients but...he insisted on leaving me samples for my friends...

It's happened to me, I'll usually stand my ground and they'll back off when they realise I won't respond to their bully tactics though you can end up in very scary situations. If they pulled a knife on me or were seriously threatening to attack me or break my stuff I'd just give them the money since I can make money again but can't if I get a serious injury and end up in hospital. Your health is worth more than a bookings worth of earning anyway.

Don't just do it anytime somebody gets demanding though most of them are  cowards and opportunists who will give it a go but won't do anything if you tell them to get lost or start calling the police. They soon bolt out the door when you don't make it easy.