They first contacted me with an invitation letter, promising a reward for filling out a questionnaire online. But then they didn't send the reward, so I contacted their service. I told them upfront, until I've received my reward, I won't participate in any more questionnaires. Months and months later, after multiple emails, they finally sent not the promised reward, but an adequate alternative. Ok, I thought, maybe I was just unlucky. So, the next time they send me an invitation email to a questionnaire, I participated again. But behold, AFTER I answered all their questions, I got a message along the line of "we have enough data of people that have your profile." That's it. No reward. You answer, put in the time and effort, and then they basically claim AFTER you're done that they don't need your data (but I can very well imagine they still grab it) and you get nothing. The reward is not for the time you invest, but for providing "good data", which criteria you don't know. Essentially, they can collect tons of data, without giving out one single reward. I don't think that's the practice of a reputable survey company.
