I've been pretty lucky, the only program I know of that has nakedly and deliberately stiffed me was GordCash, when they just baldly announced that they were going to stop paying affiliates for existing rebills. (
thread ) Fortunately, the amount involved was truly trivial because I had never got past sending them minor test traffic.
I've lost a ton more money to programs that change up their affiliate software and links without making any provision to keep the old links working. This pisses me off especially when the old links still take my surfers to the program and generate sales. But a lot of times, this is technical incompetence and cluelessness, not deliberate theft.