It's been a long term problem for me and my customers, they buy a photo, actually it's usually a series of photos, I get paid, then they decide the photo is so great, so beautiful and so wonderful will use it for their marketing piece and sell millions of dollars.
I come back to them to ask for more money and now they are not so happy with the photo. The photo is not worth 2 cents, it's a piece of shit. How could I do such a bad photo, and con them in buying and using it? Now that I want to be paid more?
I usually try to explain usage, rights...