The trouble you have with returning a console after using it just because you didn't like it is a difficult one. There's not really any valid reasons you can come up with to explain why you don't want it. If you don't like the games, you shouldn't have bought it. Can't afford to pay for it... tough, shouldn't have bought it.
The main issue is that it looks a lot like you rented the console, but didn't have to pay a rental fee for it. Now, if they allowed everyone to return consoles, what's to stop other people who can't afford one doing it when they have some mates around?
Infact, ten years ago now, I had a summer job in Game. I remember they had a used Playstation for sale, completed with multitap and four controllers; this was back when they first started doing trade-ins. A bunch of lads did just this, by buying it and using it for the weekend before returning it for a refund.
In this case, as it was already a used machine the Manager gave them a refund, but told them they weren't to come back to the shop again.