Here's the flip side (i.e., not from the perspective of participating businesses) - I hate daily deals because, as a customer, they are almost never relevant.

It's like signing up for a crappy mailing list full of spam in the hopes that once in a blue moon something useful would show up. Except, the signal to noise ratio is so poor you only ever find out about the really good deals after the fact.

If I didn't want a spa Groupon yesterday, I sure as hell don't want one today. I don't want your stupid emails clogging up my Inbox - if they were smarter about it they'd get something in my news feeds - so I can just briefly glance at it and go on with my day, instead of deleting all of these emails.

If Groupon had actually a variety of deals of interest to me (or anyone I know, really), then it might be a compelling proposition to me as a consumer. But as it is it's just a bunch of crap that few people want (or a ludicrous overload of things people want).