I've given mine 2 so far (I do it about every 2-3 weeks or so).  I know it is probably overkill to do it that often, but, I've not had any problems!  I have a big utility sink in my laundry room that I just throw 1, 2 or all 3 of my balls in, fill it up with hot water, put in some Mr. Clean de-greaser and let them sit in there for about an hour.  Take them out, wipe them off and repeat the process if necessary!  After they dry, they are nice and clean and as tacky as the day I took them out of the box!  So, to answer your question, I haven't had any trouble giving my Cell a hot water bath!