How could someone contract Hepatitis from themselves?
Poo is full of the kind of food that the little bacteria and viruses in the air and in saliva love. If you are not as clean as Bbucko suggests you be, you are ingesting poo that is dirtier than regular poo, as it has had time to attract Hepatitis, toxoplasmosis ("toxo"), and even, if you're lucky and happen to be in the right place, dysentery.
None of these is very sexy. You should clean yourself before sex unless you want a whole lotta gross stuff to happen to you, no matter who you are and who you have sex with. Don't gay men read Jack Morin anymore?