I think the people least likely to make a groupon scheme work are the new start ups. The temptation for them is a steady flow of work, but if they have all of the usual overheads, insurance, vehicle costs, wages, machine and material costs etc then the £12 they get from doing the average groupon deal doesn't cover it, let alone make a profit and without profit how can they generate sufficient funds to start more main stream advertising that brings in much higher priced work?
The notion that you can build a database of customers from these schemes is flawed, as in my experience you can never get away from a low price, add to that these people didn't even choose you, they came to you via groupon, purely because it was a cheap deal, which isn't ideal as they are never your customer, they are groupon customers.
Far better to set yourself up as a professional carpet cleaner and deliver superb quality, that is the way to build a successful business.
Simon