We dont touch them and we tell the customer it hasnt been touched, if they wish to supply the cleaning fluid by all means we will clean it but other than that its hands off for my techs. Do it properly or dont do it at all. The customer is advised either way

Well if you trust them to clean it - you can ask them to clean it. As princess says - it all costs money for labour and parts. At the end of the day - it's your car and you have the final say what you would like done to it.

Yeah I'd be surprised if any dealer touches them.. The clean them and dry them isn't quick.. Add to that the sh*tstorm if someone used an aftermarket oilless filter and the service department oiled it..