I normally check out the various deals also before making a purchase. I have found that in some restaurants the "blackboard" in house deal when you arrive at the restaurant is better value than the Groupon type deal. Same with the hotel deals. We saved a few € by purchasing a deal but got the room overlooking the roof area with extractor fan noise etc. Certainly not the sea view room.
Some deals can be good but looking at some of those on offer, they are from the same companies over and over, these guys have perfected the offer and is now part of their norm.