I decided to make beef pho in a crockpot this weekend because I had company and was short on time to tend the stove. Usually I do it on the stove for hours but I just threw it all into the crockpot and set it overnight for about 12 hours. I used several oxtails and some soup bones and all my usual seasonings. When I tasted it later in the day, it tasted like dirty dish water and nothing like it does when I do it on the stove top. Maybe it was an issue with how long it took the come to a boil? I think it must have taken a good 4-5 hours to come to a simmer. That sounds like a long time in the bacteria breeding zone. I don't know. It just tasted awful.