I've never done telemarketing, but I have done phone surveys, which is a slight step up in that they don't have to follow the DNC rules. If people were really rude to us, we would laugh about it after we finished with them. It was a way to cope with the job. There were occasional weirdos who got a little perverted, but those were fun.
I hated that job, but I did learn one thing. Nobody ever wants to take the surveys, but they still believe the numbers in the polls.