Heritage tourism for realtors

Mitch Hagmaier writes from Pennsylvania:
I had a guy try to sell me a house by claiming that the space under his detached garage might have been an Underground Railroad hidey-hole. I told him that somebody across town had already gotten ahead of him & put up a plaque on their alleged UR station-house. I didn't buy the house in the end, but it had more to do with the disastrous state of its foundation than the root cellar he was on about.
As every school child in America knows, slaves often stole the master's automobile and then hid under free state garages. A recent study shows master preferred Packards where slave ownership was 100 souls or fewer. On the really large plantations, master drove the Duesenberg.

p.s. I think the guy with the plaque risked scaring buyers with potential historical property restrictions.