I made websites for a couple of Mistresses, in exchange for 4 hours of services.
When it came to it, and I was on my way for the first reward, the text messages went a bit weird, and it became obvious that they had a client who wanted forced bi, and they were using me for that and my reward.
I didn't bother turning up and just let the websites slide.
I've often done exchange of services with my massage skills. I know it sounds corny and I only ever get anything by word of mouth recommendation, because you don't get anywhere saying you are a good masseur. I do get asked back a lot, and it ends up being about a 4:1 ratio, as in an hour of massage gets me about 15 minutes, which is about fair enough, as good massage rates are about £35 an hour, and the girls I do are in the £140 bracket.