Think you know (or are) a hardcore Twilight fan? You might second guess the extent of your friend's love for all things Cullen after seeing the extreme devotion on display in the homes of these super fans. [People] via [ONTD]
I don't understand the purpose of mocking things that make a person happy and don't harm anyone. Is it to make us feel superior? If this brings her joy—whether it's because she's socially awkward with real people and this fills the void or simply because she likes projecting her level of devotion visually and collecting/making fandom things—more power to her.
Twilight and this style of decorating wouldn't be my choice, but I'm not going to laugh at her for it.
Also I think this is also a very heavily gendered criticism in a way I am not at all comfortable with—I've met a number of men with Star Wars tattoos and full-house decorating schemes, but when photos of them get posted, it's not derisive, it's celebrated. The fact that Twilight is a functionally 100% female fandom makes it a target of denigration.