Obsessed wrote:
But they said up to 60% off. So, if 1 item had 60% off, and the rest of them had +60% the sign would still be correct. So the consumer sees the sign and thinks "Oh, a sale" and then buys something that may have just been raised in price, thinking it must be a good deal.
I don't know.
Where I live, being correct is not good enough. Advertising must also not be misleading or deceptive (this standard is explicitly required by legislation).
So for instance advertising must be clear if there is limited stock discounted. A store that discounts its last 10 stereos (in a line) by 50% and advertises this outside the store, must include the fact that there are only 10 such items available in the same advert.
For in-store advertising, if discounts are offered, the advertising must be clear what stock is discounted, by how much and the price before and after discount (this can be done by a sign as described by the OP, but the price tags of the actual items would have to individually identify whether they were discounted).
It is considered deceptive practice to raise prices to then introduce a false discount, and if caught, a retailer would face fines.
However, it's important to be aware of consumer protection laws because these things are not uniform from one place to another. If you know what is and is not allowed (in regards to advertising) then you'll know what to look out for when shopping.