Let me be more specific, you don't want to remove the natural protective coating that the oils give to the metal. Using soap and degreasers do exactly that, which can cause rust. Not to mention the cleaners chemicals and crap, you don't want that being heated up and smoked with your food.
You want to remove ash, grease, and food particles. That is easily done with simple stuff, like a rag, water/vinigar to cut through heavy grease, and scrapper (razor for glass or plastic for metal). In the end you don't want moisture to be retained...otherwise the heat is high enough to kill bacteria anyway...having it cleaned out with soap or other grill cleaners seems just silly to me.
Just from personal experience, I once used those cleaners and i swear i could taste it in the food. I thought i did a good job cleaning, it looked brand new. I even made sure to do a dry run to burn off the stuff...but even so...i would never do it again.