Thanks to walkdmx for raising the issue of 'opinion theft'

"it is considered opinion theft by the ethics associations which these surveyors must belong to. Complaints are vigorously pursuued at the top levels of the companies, and I have had recognition withdrawn for several companies from various associations which then list them as Unethical. So you do have very good options to pursue those who steal from you."

I just completed a survey through E-rewards that linked to (intellisurvey link removed by moderator) that required 35 minutes of my time with a reward of $8.25 in E-reward currency. After completing the entire survey, I received a screen message stating:

"Thank you for your interest in this study. Unfortunately, this study has received the number of responses required from your particular survey group. Your e-Rewards account has been credited the partial credit amount."

I reported it to E-rewards and we'll see what happens.