Being a "professional survey taker" is another thing that might DQ you from some surveys, believe it or not.
Being a professional? How utterly bizarre. If FC, or anyone else, sends them to me then surely it's because they want me to do them.
That makes absolutely no logical sense whatsoever - sending me loads of surveys and then penalising me for doing them.
The firms who actually run the surveys may maintain an internal list of frequent survey takers, probably identified by anonymized browser fingerprints. If they had such a list, it would not be given out to anybody, so we have no way of screening you out before sending an invite. Think about it: they would have to send a list of hundreds of thousands of email addresses to every partner that runs their surveys (and they'd pass it on to subcontractors, too)... privacy and data protection nightmare. The market research firms are pretty cautious about protecting user data - it's their meal ticket.
As far as I know, it depends on the sensitivity of the survey and the end client as to whether a "pro" would be DQ'd or not. While I have some ideas as to why they might DQ very frequent survey takers, they are really only speculation and thus I'll just have to leave you with a shrug for an explanation. We can't control individual members' experience with surveys, because every individual's experience is different and determined by a huge number of factors, not the least of which is your personal survey history (whether through this site or another). I can only suggest that if you are seeing a really low success rate (say, 15 DQs in a row) with surveys, you might want to take a break for a while. FC members, overall, qualify for a pretty high percentage of the surveys that they click - higher than industry average. I know with all the complaints it is hard to believe, but it's the truth.