Were you using them to push a service or a hard product? Just asking out of curiosity. We were approached about a product push about a year ago. It became a big hassle and we wound up not doing it. It was WAY front loaded for them. Looking back, I don't know where the juice would have been for us.
It was $30 worth of product (Garden Center) if they bought the Groupon for $15. Even after it expired it was still worth $15 to infinity and beyond; they STILL show up, two years later! I should’ve just stood out front handing out $20 bills, LOL!
Most useless promotion marketing ever did...