stopped at page 6 so forgive me if this has been said
fyi, there are two sphincters (sp) in your butt. the first is right at the opening (exit?) and the second is a bit further up. your deficate (sp) stops at the second one until you start to go to the bathroom, and it is far enough in that most guys dicks aren't long enough to hit it
so no, you won't get shit all over your dick, and if you use condoms (which you should for various reasons) then you won't have this problem anyways! your ass is actually a fairly clean part of your body, even though garbage comes out of it, it's not a messy shit hole like some people apparently think!
also, a guys prostate is against his intestines (near your ass), which means when some guy is pounding your ass his dick is going to be rubbing against your "pleasure spot." too bad most guys are too concerned about looking like a fag to actually experiment with thier girlfriend (or a guy
)
the more you know