Groupon is basically a coupon brokerage. They have absolutely nothing to do with the quality of store, product, service or restaurant, or store hours, in the same way that the printing companies that print the little paper grocery store coupons are not responsible for any of the products/services.
So do your own research as to whether the store/restaurant/service you are buying a discounted coupon for is worth it
in the first place. If it's not the type of place you would go in to buy things
before the Groupon discount, don't expect the products or services to be
better just because they offer a Groupon. Groupon is a place that helps them
advertise to a wider, online audience than they'd have without it. It is
sometimes a way to find out about LOCAL stores/restaurants/services that you wouldn't have found on your own or tried before.
Always go to the actual business' website to do your own research before buying a Groupon.
That being said, my local area Groupon offers a couple of great Groupons. One for a health food store I already shop at, so I get an extra discount every few months. (Coupons are good for repeat customers.)

And I found a new company I like, that I wouldn't have found on my own.

The haircutting coupons weren't any good as they were always junior cutters with very little experience, and I could have gotten a better cut at a Supercuts instead.
