I use one with some gentle ivory soap on both of their chin on occasion but I don't do the back of their head/neck. It never seems to get overly dirty and ..I kind of like the smell of that area (crazy cat lady alert). It's one of my favorite snuffle spots.
Never bathed a cat in my life unless they've needed it, or unless you have allergies. Plus, it may seriously stress them out. Some people say to bath cats to get them used to it in case they need it later on but I've bathed both my cats, once when Blaze peed on himself and once when Blacky had poop on herself they didn't go crazy of anything despite never having had a bath before or showing any interest in water - and they were in their teens.
It also seems equally pointless to use a washcloth or something in certain areas... they may not mind this so much, but what a waste of time.