Go smell your toothbrush. If you’re like everyone else in the world it smells like a foul mixture of bad breath and crusty toothpaste. This is because you never clean the damn thing, you just give it a quick rinse under the faucet. You are under the illusion that toothpaste cleans, that toothpaste is like soap. Guess what? Toothpaste does not clean your brush, it just makes it smell like toothpaste.
If you want a clean toothbrush, soap it when you are done. I know this sounds crazy and OCD, but first off I am not telling you to soap your brush, I am simply saying if you want a clean brush this is the way to do it. Second, you are sticking this nasty, festering, bristly nyon into your mouth everyday. This is not your kitchen sponge, this thing is going into your mouth.