So, you spent $X and completed a survey after an employee offers you ten dollars that requires you to return to the vendor and purchase an additional ten dollars of their merchandise within thirty days. Assuming a fifty percent markup and two ten dollar purchases, they sold you ten dollars (cost) of goods and received ten dollars of cash. You parted with ten dollars of cash and, ere lured into that store a second time to 'spend' the ten dollar coupon after completing a survey (your time and effort) for them.
If you 'do the actual Math, you might discover that you did them a favor - esp if you consider that, in addition to completing their survey and buying more of their stuff, you appear to be lauding their behavior as exemplary - a valuable advertisement of the sort "you can't buy?"