Mormon missionaries should just leave if you tell them you're not interested. That is what they are supposed to do. They aren't supposed to harrass you or cause any trouble. Sadly we've got our dumbasses, like every other single organization in the history of the world.
And yes, we're a cult of 12 million people.
Look guys, I've been there, done that, on both sides of this fence. The "god squad" people are doing what they think they are supposed to do. And yes, some of them are rude morons. Somehow doofuses manage to sneak into every single group.
And for the answer the door naked, show them a gun, tube of KY, whatever, those things usually made me laugh and broke up the monotony. I had a great time. I loved people with senses of humor.
As soon as somebody said they weren't interested, I said thanks for your time, and boogied out of there.
I can't speak for the other religious types, but the Mormons are there because they're trying to do what they think they are supposed to do. For most of us who choose to do that kind of thing, we go someplace far from home for 2 years, usually from the age of 19-21. We aren't allowed to do pretty much anything fun. One day off a week to do laundry/run errands, etc. The rest of the time you work/teach/find people to teach. No dating. No TV. No non-church music. Nada.
Now the door to door stuff is called tracting. Tracting sucks. The main reason that LDS missionaries tract is because there currently isn't ANYTHING else more effective to do. But it beats twiddling your thumbs, and for most of us, we went on a mission because we wanted to work. And occasionally, seldomly, you actually find somebody who wants you to teach them.
It has been 10 years since I've gotten home from mine. It was tough. I got shot at, attacked by dogs, chased by drug dealers, and hit by a car. A lot of times it sucked. But I had fun.
If you are treated rudely by LDS missionaries, and they don't leave when you say you aren't interested, or they are just jerks, or whatever, and I'm dead serious here, send me a PM with your town, general location (neighborhood will do) and the date, and I'll take care of it. I will contact their mission president and let him know that his Elders are setting a bad example.
But please, make sure they are Mormons first.
I found that about 95% of the time when somebody was really ticked off at us they were thinking about a different religion. (for example, the guy who posted above about the cute girl his age who spat on him when he said he was Catholic. News flash. If she was by herself, then she wasn't a Mormon. Mormons never work alone).
Wow, this is massively off topic. I'm not setting a very moderatorial example here. Sorry.