It's that insane greed that puts me off it MrsJayy
But I do get a warm rosy glow when
a) somebody takes some piece of old tat, obviously thinking it's going to be worth millions, and it turns out that their Great Aunt Hermione wasn't gifted it by an eccentric millionaire who had it specially commissioned for her from a Paris jeweller, but that it actually came off a Woolworth's barrow and is made of low quality paste.
b) someone takes something that they just want to show for the novelty value (e.g. family album from before the first war, and the mystery bloke standing next to Uncle Herbert beside the abattoir, juggling with cow's shin bones, turns out to be the Crown Prince of Schleswig-Holstein whose life he had saved at the Battle of Balaclava) and it's worth £££. You can always tell by the faces whether they are genuinely surprised at the value.