Lets have non of that bowing/sectret hshake/foot in the water stuff, Im the same as everybody else here -part nuts :
Well its down to if you want the job or not, pilks say only clean with a soft wet cloth and water, hence the micrfibre wand and plenty of water. I would explain your side of the situation to them, Pilks have a warranty which may be voided if incorectly cleaned. Then get them to sign a simple understanding that they are now aware of the self cleaning situation and wont hold you responsible etc or for any scratches that may already be there and get it signed or walk away.
Personally it may be self cleaning but doesnt usually work, in other words its an expensive cobble together salesmans wet dream