Yup - I agree with mouser. People are increasingly worried about getting ripped off (with good reason, evidently) so best to be upfront and acknowledge the potential. I'd advise customers to write down the part make/model/part number, etc of the components in their tower. Perhaps you could generate an inventory sheet for them to fill out with you when you first open up the computer. Of course, this is probably OTT, but after watching the YouTube video, it's something that I, as a potential customer, would do on my own anyway (but then I have no problem opening up a computer case and
mucking tinkering on my own (just pulled all three of the household notebooks to pieces to clear out a year's worth of dust, lint, feathers (cushions on the couch), and hair - also found the magentic tip from a Magnadoodle pen in my wife's notebook, that can't have been doing anything any good!). Even so, this strikes me as a good way for you to be open with people and to allay any fears that they might have after viewing the "House of Horrors" episode.
PS Disappointing that Mike Quigley is likely continuing to con people. He's a scoundrel and not to be trusted (hopefully this thread will come up if any potential customer is savvy enough to google his name!).