IDEAS: How to fail when running a shop

FAIL to place shop signs in a proper way or, more generally, FAIL to study and learn how the shops work

A shop sign belongs to the chest below it, even if it is attached to a chest behind it!
A shop sign belongs to the chest below it, even if there are other chests to the left, to the right or above it!
(IIRC, this information was included somewhere on the website in the past, now I didn't find it in the wiki.)

FAIL to double-check your shop signs

Making shop signs and changing shop signs to adjust the prices is tedious and error-prone, especially in a large shop with multiple shop signs per chest. It is easy to make a mistake.
An error on the shop sign will either make that chest-shop unusable, or worse, it will make abuse possible.
Some people can't help themselves but to abuse shop-sign mistakes (which is, by the way, scam and thus perm-ban offense). It happened to me due to a shop-sign mistake, that two players have not only drained all the rupees from the shop, but did proceed to empty the whole mall. It is very tedious to recover from such abuse.

Hey MM I am curious. What chests were they exploiting? Like how did it all happen? When you say they drained all the shop rupees are you referring to your entire rupee balance, or the total of the previous income made directly from the store in the past?

I assume the mistake was that one chest had a sell price lower than the buy price. Such a mistake is very easily made, and with one such mistake players could drain the rupee balance, and buy more items with the rupees they 'earned' from it.
... at least, that's what I thought. I just got onto EMC and found out that it is impossible to create such a sign. I wonder now if it was possible in the past, or if some different kind of mistake was made, maybe the same issue but spread across two signs!

I think it would definitely have to be 2 signs, as your correct, 1 sign can't have a sell price lower than the buy price. I suspect they made one sign for some items (probably high value ones) and the forgot they had that sign and made another in a different part of the shop later. Then the 2 players noticed and abused it to drain all the rupees.