[TWAndrews]

This is a plausible theory. However, there are equally plausible theories that have a Groupon promotion functioning as a loss-leader and reaching a much broader customer base than a company's traditional marketing otherwise would, with some Groupon purchasers becoming loyal customers.

Either of those are possible (and I'd say it's highly likely that examples of both exist amongst the group of companies which have offered Groupons). The telling thing would be the data, which would resolve it pretty definitively for any giving promotion.