the Foreman has to be one of the easiest things to clean. little bit of dish soap, a sponge, and just wipe it clean.
I've forgotten to clean it after using it a few times and still a couple days later, stuff just wipes right off. Personally, I don't ever smell anything I may have cooked previously on it.
Fish usually has a strong smell to begin with so that may be an exception. I know when I make tuna fish, I wash my hands after draining the water out of the tuna can and it seems like my hands smell like tuna for the next hour or so after I wash them 10 times.