Price-conscious consumers will absolutely take a good deal but build no brand loyalty. They'll hop from sale to sale. Businesses live and die by customer acquisition costs. You're better off offering deals to customers who've already demonstrated a willingness to pay near-MSRP regularly, and offer deals if they start dropping off, to get them buying again.

Groupon just proved, at a larger scale, what was always present in consumer behavior. Of course it wasn't going to be sustainable just like click-through rates for ads dropped off once people got used to their placement at a particular location in the search results. In this case, Groupon capitalized on small-business owners who had a poor grasp of how consumers work.