I've had several in the past week that took a while and included answers I had to write. Then I got DQ'd at the end. Besides being angry at wasting my time, I always feel gypped because they got all the answers they wanted without having to pay.
Luckily, this doesn't happen nearly as much as it did when I first took surveys for a few months 15 years ago. It got so stupid I quit, especially when the site I used got sold to somebody who raised the payout from $10 to $25. I knew I'd never get that much because payouts per survey were much less then. After I quit, the idiots kept pestering me with e-mails begging me to come back.