You shouldn't clean it ...
Really. Some of them are getting very delicate. Doesn't take much to rip the transfers right off.
Whatever you do, avoid dish soap. Those "grease lifters" also do a nice job of softening most anything else. Windex is hard on a lot of the faceplates also.
I'll usually just do a rinse and light rub with a finger under cool water. Blot, don't wipe. If you have some nasty stuff that doesn't want to let loose, maybe just a tiny bit of baby shampoo.
And ALWAYS test just a small section first.