Since I live in an apartment complex, we seem to be fair game for any and all types of solicitors, even though there is a "No Solicitation" sign on the office door. Of course, many of these solictors don't go anywhere near the office, and often come after office hours anyway. After trying, and failing, to rebuff their attempts (most don't take a kindly, "no, thank you" as a suitable reply), I affixed a "No Solicitation" sign to my door. Still, the church groups would descend upon me, and try to "save my soul." (Apparently, they don't see "selling" their religion as solicitation). Again, polite responses didn't work, and I hated how I would have to get stern with them to get them to go away. I found myself frustrated that I would have to ruin whatever good mood I was in just to get some peace from them.
Finally I had a sign made that says "No Religious Zealots".
I've yet to have any unwanted knocks on my door!