Coupon ethics?

Many coupons, offers, and promotions at stores involve many exclusions and restrictions in order to make sure that the company offering the coupon is suffering as little loss as possible. When those few and far between times arise where you find a coupon or an offer that neglects to specify certain things, is it ok to take advantage? For example, purchasing a 1 dollar piece of candy at the register in order to get a 12 dollar bottle of lotion for free when you get a Bath and Body Works coupon that allows you to get a free item 12.50 or under with any purchase? Or trying on a pair of jeans you have no intention of buying at Delia's just to get a 10 dollar gift card? Do you feel an ethical obligation to multi-million dollar corporations that reap unbelievable profits off of its customers and even it workers? Or should ethics always turn a blind eye on circumstance?