Dear 100 Hour Board,
From what I understand not washing your hands after using the bathroom can lead to disease (either in you others or both, I'm not sure). If that's true, why doesn't having sex cause those same diseases (for this question, I'm excluding STDs)? I know of urinary infections, but what about other things? Also, say two people get married and both are STD free; is sex unsanitary?
-doesn't like germs
So, poop is a thing, and it's the main problem with not washing your hands after using the bathroom. Fecal particles can carry a lot of bacteria and parasites, and coming in contact with them (when you wipe after using the bathroom, for example), puts you at risk of getting those diseases. So not washing your hands after using the bathroom can make you sick, if you then eat something, or touch your eyes, or something similar that allows that bacteria to enter your body again (it's usually okay in your colon because your colon has its own bacteria to keep everything in check). It can also make other people sick, if they come in contact with those fecal particles (for example, if you shake their hand, then they make food before washing their hands).
The diseases you can get from touching poop include E. coli, pink eye, Salmonella, rotavirus, Giardia, and Cryptosporidiosis. You can get a lot of others, as well, but those seem to be the most common ones. They all have different symptoms, but the main unifying factor among them is that they're gross and awful, and mainly preventable if people wash their hands.
So no, having sex can't give you the same diseases as not washing your hands after using the bathroom can, unless for some reason your sex involves poop, which for everyone's sake I really hope it doesn't. Sex in and of itself isn't unsanitary, though. Yes, it's probably a good idea to take a shower afterwards, just to clean everything off, but that's more because it's gross to be all sticky rather than because you'll get diseases if you don't.