I think as long as the requirement to purchase a certain quantity is clear, it's fine. That is the store's choice, especially if they're having the sale to clear inventory. Now if it's not clear, then that's a different story. To me, that's bait and switch.

Ellis, I think I must be misunderstanding your comment above about "buy one, get one" offers. What exactly are you looking for stores to do in that situation? Those seem pretty simple, with the buy one at regular price and get the 2nd of same or less value at a reduced (or free) price. Are you expecting to only buy one and get it at the reduced price?