Here’s a scam that just occurred to me while at the local big box building centre. I didn’t try this, nor do I suggest you do. Consider it for discussion purposes only.
While ordering some paint, I noticed they have a rack of mis-tint all at a flat price… about a third or less than regular price.
So the plan goes like this: Order the paint you want. The good stuff. Don’t skimp. Walk away.
Later, come back to the store and check the mis-tint rack. Grab your paint and take it to the cashier.
This is basically a variation on Abby Hoffman’s free pizza scam which no longer works due to caller ID. (Order a pizza with weird toppings for a bogus address. Pick up your free pizza behind the store when they throw it out.)