Yeah. Still a waste of time. Sorry. Disney did not have it the first few decades of operation and those were the most "magical" experiences ever to be had at a Disney park in Florida.
No need for explanation of what it takes to be "certified" to be able to do the drawings. I am not questioning that and respect your ability. You can leave a guest with a smile without the art. DIsneyland did not have it when it first opened and I would say it turned out pretty good.
I also have to disagree that there are not too many GSM's that would allow CM's to do nothing (including water paintings) on the clock "waiting to go home." If they do then they are a poor leader and should be re-evaluated.
What good is it to refer someone as a Custodial Guest Services Cast Member if it is internal? If the guest does not know that is what you are (which you are not because that is why they have Guest Relations at each park) they would publicize it.
I looked and no mention of "Guest Services" here:
http://parksjobs.disneycareers.com/careers/custodial-jobs