You flush the toilet right? You touched the door?

Your crotch is probably the sweatiest region on your entire body. Your penis is pretty darn filthy, even if you can't see the thousands of microorganisms living on it.

There are more bacteria in your mouth than on your dick... What now?

Yes the mouth has evolved to do that because your throat is especially susceptible to pathogen infection so the saliva traps the bacteria to keep you from getting sick. That's also the reason for nose hairs. However humankind has always washed and bathed ourselves before we even evolved into the homo genus. How do I know? Our closest living relatives do the same thing by instinct.

That's what now.

that's what your mouth is for.