As for the original discussion, I wanted to add something: If you're going to do this, first test your crock pot's settings. Fill it with lukewarm water, then put it on warm, for instance, and check every hour for the temp. If its lowest setting gets higher than 140F (60C) in less than two hours, it's completely safe. On warm, mine is about 180F (about 80C), so it's fine. Low and high bring it up over 200F (about 95C), the only difference in the settings is how quickly this happens. Last but not least, for the most safety, I would briefly microwave/ bake/ saute any new solids going into the pot over time, and bring any new liquids to a simmer (microwave's fine), so that they don't drop the temperature of the crock pot. If it's a big piece of meat, just get it to room temperature (thaw in the fridge first if frozen, then half an hour on the counter), and sear the outside well before adding it. I actually have an "endless soup" going now, because of some issues with my fridge. I don't like and can't afford waste, but also can't safely store leftovers right now, so I decided to keep things hot in my crock instead. I made an initial pot of soup, and then we ate most of the solid bits with a little of the broth. I added some more water and let the little bit of leftovers sit hot overnight. The next day, I put in new meat and veggies at the time I would have put it in, if I were making a fresh crock pot meal. I also add more/ new herbs, because the scent of the herbs breaks down after being held hot for a long time. The older items do turn into a sort of mush, but they make a very rich base for your new items, which won't be overdone if you do it this way. I actually like it so much that I may keep doing this, even after the fridge is fixed! lol That said, I personally will change my "endless" pot after three meals. After all, it could end up tasting quite same-y after a while. When you work in food service, the rule is generally not to keep prepared items for longer than three days under refrigeration. Obviously, we keep things for longer in our refrigerators at home, but it's a good general rule of thumb if you're concerned about safety. And, discarding a little leftovers every third day is better than discarding leftovers every day, or leaving them to while away in your fridge, be forgotten, etc.
To the guy with the crappy crock pot:
New crock pots are not the issue. You got a cheap crock that's probably made in China, or some other place where they don't care. Get something better. I have a newer crock pot from around 2014, and it has never given me any off flavors. This is not a new/ old issue. This is a good ceramic vs bad ceramic issue. My crock pot was about $40. You don't have to break the bank, just don't get a skeezy off-brand cheap-as-dirt model. Get a crock from a reliable brand name. Mine is a Hamilton Beach. It's not the best pot ever, the rubber seal actually takes some heat damage if it's run on the high setting for too long, but said damage is superficial, not functional. Rarely sticks, can be cleaned with an SOS pad without taking any damage at all to the finish, and not a single off flavor. I actually bought this new pot because an OLD crock pot was given to me, and I was tired of that weird taste you're describing. It was very slight, but it bothered me.