Most of the survey companies I’ve tried are fairly straightforward about how their rewards systems work. Every time I receive an email invitation to take a survey, I know exactly how many points it is worth before I even click the link. Also, most sites have a page that tells you what your points can be redeemed for.
A few weeks ago, I signed up with a company called Big Idea Group (BIG). You qualify for “clubs” based on your demographic information. Each club has a series of activities where you answer questions about features and usability of a particular class of products, including making suggestions for what features you would like to see on a new product.