It is difficult because as dealers we try and be as helpful as possible and sometimes bend to a customers wishes but there has to be a point where enough is enough. I was chatting to somebody else about my BMW guy and this tread and he told me if a customer asks to plug in a scanner, take caps off under the bonnet or generally do anything out of the ordinary he asks them what qualifications they have. If they turn round and say they're a mechanic, in the trade etc he explains to them if he lets them inspect the car he will then have to sell it as a business to business trade sale and all warranties become null and void. He's never had a customer come back that agreed to this but I wonder how it would stand up if it every got to court?