Taken from slashdot and written by by Southpaw018 (793465), not me:
I worked for the telemarketing department at MBNA for a while. They're a good company, and while it wasn't my favorite job ever, MBNA is a good business, and they follow the telemarketing rules. (If it's any testament, I carry an MBNA credit card.)
Anyhow, in answer to the second part of your question: If you say "take me off your list" or "don't call here again," if the telemarketers are following the rules - and they're subject to MASSIVE fines if they're not (like $1000+ per phone call in violation), your phone number will be removed from the marketing programs you mentioned for two years (or if you say "all" your lists, all their marketing programs).
The magic words are "do not call list" or "ever." The better choice is "do not call list." If you say "Don't call here," it's still two years. However, if you say "Do not call here ever again," or if you say the magic phrase "Add me to your do not call list," your phone number will be added to their federally mandated do not call list for a period of ten years. Also note that once you say one of those two phrases, they are required to give the three pieces of information they need for every call if they have not yet mentioned them, and then terminate the call immediately. (These include their full company name, a telephone number at which they can be reached, and....the third I don't remember. Oops. But! I do remember MBNA being so paranoid about it that we were even required to say the phone number to dead air if someone hung up on us - it was always the last thing you gave them, and we were recorded every second we were on the clock, even while not on a call.)
Again, this is if they're following the rules. No one likes a telemarketing call at dinnertime, but the bad guys do a hell of a lot worse than that.
Oh, and I can't comment on surveys or political calls. This is just commercial stuff - the guys who aren't out to make $ have looser rules.