How long is too long to cook meatballs in sauce? We use ground Chuck for the meatballs when making meatball subs. No spices or chopped onion, just meat and the meat sauce is a basic tomato based concoction. Then we cook the meatballs(raw) in the sauce in a crackpot for about 10 hrs! When we serve it, the sauce has cooked away by 95%. What I need to know is can you overcook meatballs and/or sauce (on low setting)? They always have a terribly strong and bitter taste that ground beef shouldn't have.
That long time in the crock-pot sounds bad to begin with. Ground meat should be just cooked to a safe temperature -- any more and it will lose moisture and get tough.

The bitterness could come from prolonged exposure to the acidic tomato sauce. If you've ever made ground taco meat and over-seasoned it with lemon or lime juice, it will often taste bitter or astringent.