I've had some of those and usually when I inform customer service with full details of the survey, they check into it and give me full credit. Some of the survey providers try to cheat e-rewards and us when they ask 10 mins of questions and then say we don't qualify. (Or, worst case, don't even provide a link back to e-rewards, so we get nothing!) Those are obvious cases of harvesting data and trying not to pay for it and it's no doubt best if you can give them specific data about the cheats so that they can deal with them.

Most of the time, surveys either reject you within 5 or 6 questions, which is pretty good value for 25-50c, or run to completion and pay the full amount.