Aside from the classic of not allowing you to return a game which you could copy to keep playing (a totally understandable reason, yet unfair since "improving" the marketing of a game is a common practise, piracy being illegal, and demos are almost absent from the entire industry), I mean buying digital content like a premium skin for your character, a vehicle, etc.
In general, I've seen so many times companies twisting the reasons to not to refund anything that it makes me think if we have any right at all. For them, playing with that even once is an "added value service", so it's not refundable. You usually don't have other ways to try what you buy, and even if they have something like a test server, it's usually quite different from the experience in the real servers (for instance, everybody using premium consumables to get a huge advantage)
Not to mention how many lines in the EULA's are illegal. More than a legal document it's almost like a wish list for the company.
What do you think?
PS And yes, I've bought something, I regret doing so, and given they are not willing to refund me I'm even thinking about having a talk with my bank to cancel the charge.