Because of their attitude I won't be back, that's the cost for making an assumption about me as a customer.
That's the rub, really. I find it hard to blame Groupon themselves for stuff like this (though certainly Groupon has other aspects that are complaint-worthy). If you're going to treat customers poorly because they've taken advantage of a deal, I don't really want to be your customer. And if it's such a bad deal for you, as the restaurant, why are you participating anyway? If you really feel that the extra customer acquisition is worth the lower revenue for the sale, then you should be happy when Groupon customers come in. If you don't believe it's worth it, why do a Groupon deal at all?
True, but the waiters and staff are the public face of your restaurant. The owner/manager doesn't get involved in every meal they serve. If you suspect your staff will get cranky with Groupon customers, you need to fix that. I don't care if that means firing the worst offenders and making it clear that you won't tolerate such behavior, or if it means ahead of time declaring that you're going to "fix up" bad tippers behind the scenes by supplementing with the restaurant's cash. It really doesn't matter to me how they resolve the situation, but the owner of the restaurant is responsible for giving his/her customers the best experience possible.
That's the rub, really. I find it hard to blame Groupon themselves for stuff like this (though certainly Groupon has other aspects that are complaint-worthy). If you're going to treat customers poorly because they've taken advantage of a deal, I don't really want to be your customer. And if it's such a bad deal for you, as the restaurant, why are you participating anyway? If you really feel that the extra customer acquisition is worth the lower revenue for the sale, then you should be happy when Groupon customers come in. If you don't believe it's worth it, why do a Groupon deal at all?