My startup -- http://feastery.com -- was founded to address these problems for great restaurants. In general the issues around retention and customer quality have been around since the beginning but have been largely ignored by most writers. We match high-quality customers with great restaurants, and economically sensible offers. We help restaurants deliver a unique experience (not merely a discount) and we track retention so we can definitively prove ROI. It's a better model for our members and our restaurant partners. If you love food, request a membership here: http://feastery.com/request_membership </shameless startup plug>