Advertisements All Over Your Dashboard
Worst Example: Xbox 360 Dashboard
Asking your customers to pay for an online service they recieve free on literally every single other platform is one thing, but having the audacity to plaster their experience with advertisements afterwards is unacceptable. When Microsoft is pulling in $50/year for each user connected to its service, there is no reason why they need to put ads on the service save for unparalleled greed.
Now, you may make the argument that you pay for a cable subscription on your television and still see ads there, but that's an exclusive service that can't be obtained any other way. They've got you by the balls and you don't have a choice. The thing about Xbox Live is that it's not the only service (it's not even the best), and every competitor does the same or more for free.
The Solution: Offer a free version of Xbox Live with ads and stop serving them to Gold members.