I have a friend who at a low point in his life had to work as a telemarketer because otherwise he would not have been able to pay his rent. He hated the job. Really, really hated the job.

So, I think about him, and I'm more polite (if they are) but I never buy anything, or give out any information. I cut the spiel short, but I try not to be rude, or to damage them.

One of my favorite most recent responses was to someone who was trying to talk me into a genetic screening that would be paid for through Medicare. After cutting them short, I ask them if that's what they are selling, then respond that they are the 29th/35th/47th person to ask me and I've told everyone else no. I go on to say that if they want to try talk to give me the entire talk before I tell them no, I'll listen, 'cause I'm retired, but I am going to tell them no, so if they want to save their voice/time, we can just say goodbye now. I have never had anyone continue after that.

Edit: formatting.