the whole debate about groupon is whether or not you can make a profit on this . I can see the main defence grouponers are using is they want to build a customer base fair enough, will you get repeat work from it - i would say some but not many when you mention your real prices as they will expect coupon prices in the future, will you get recomen yes you will because its cheap.
groupon has its place but i would say its more for selling of spare or over stocked goods in the retail sector .
personally i hope it falls flat on its face because its de grading the whole service we are aiming to provide.