Today I tried 3-4 times to qualify for survey, answered ?s on one for 10 minutes just to be told I didn't fit what they were looking for. So then suddenly I got the you have exceeded daily limit page!! I didn't even qualify for one, so how could I have gotten that! And yesterday's did credit, so it wasn't that. Anyway, I went ahead and tried with a different email addy and got one - so I hope that was OK.
I've already had 2x times where somehow I ended up with 2 credits; I don't want it to happen again and have people get suspicious - yipes!