I've used Groupon several times, and I've never had an experience like that. I don't get the feeling that I've been treated differently or badly after showing the Groupon.

>Bad restaurants use Groupon because they have to - and any place that can discount so much for their customers makes me question how ridiculous their prices are to start.

In my experience, the restaurants that use Groupon are mediocre to good. Maybe it's a regional thing, but there are so many restaurants here that even many good restaurants aren't very busy.