Circular adds

So, A certain department store always sends out a couple different sales adds every week. The paper is always a nice add all in color and all the latest styles for the whole family. On the front of the paper is usually a coupon for 20% off your purchase which is a great way to catch your attention. So many times I, along with couple family members, find several things to purchase there and take everything to the register and cheerfully hand the cashier my coupon. "I'm sorry, your items are excluded from this coupon"...you mean out of ten things, the coupon wont work on not even one? So I read the fine print on the back of the coupon and there seems to be about a hundred exclusions. So I guess the add did what they intended it to which was to get people in their store. But it is annoying to find out their coupons are almost useless.