Sold a car a while back with only some scrappy receipts for servicing from the guy who serviced it locally for years. Hardly convincing, but genuine nonetheless. The tyre kickers drove me nuts about it - bitching that the engine was dusty - like we have a gravel driveway they'd just driven over FFS, the oil hadn't been changed and so on. And worse, letting some of them drive the thing was amongst the worst experiences of my life. Shit they were bad news - and I hope like hell they were not representative of driving standards out there.
I didn't play, and told them that a deposit and promise to buy would get a full service, and that they at least knew what the car looked like as was.
Turns out the first serious buyer said that was good, didn't argue about the price all that much and gave me a few hundred bucks and said he'd be back with the rest the next week-end. He got a tuned and detailed car with all new filters, plugs, leads, distributor cap, oil, brake pads etc. In short, a going concern he didn't have to do any work to at all. I did tell him to get the wheel alignment checked, because I didn't get a chance to have it done.
Not sure I'd trust anyone to do the same for me though:-)