I've only had Mormons show up once. I invited them in and had a nice chance sit down and chat about some things. I learned one of them enjoyed high-fantasy novels, so I gave him some of R.A. Salvatore's work. It was most of the DemonWars saga. I was done reading it, so I just let him have the books. It was amusing because he was all excited, but you could see his friend was visibly a little weirded out to learn this guy read high fantasy stuff.

So they left on friendly terms, and I never took their book. He did take my book though.

Sharky:1
Mormons:0