[G Griffin]

I can just vision  car sales men laughing at you

I charge extra for that.
I do the office windows of a debt collecting agency. I do the windows and they don't pay. They then chase up the debt and usually get me half of the agreed price.
It's better than nothing and they've saved me a fortune over the years.

[rosskesava]

I clean the windows of a tailors every week. The agreement is he doesn't pay me cash but when the £10 a week bill gets up to £200 quid I can pick what I want up to a value of £300 and no change given.

I also clean the windows weekly of a falafel place, a restaurant and a cafe all of which is exchanged for food.

I like it because most times I get more than the value of the work and at least three times a week, I eat for free.  Plus on other times if I buy food, I get discount anyway and often extra thrown in for free for doing odd extras for them.

If the place has what I want, I'm all for trading services for what they sell. For me, it's a great way to do business and beats cash because both sides benefit.