Dexter is socially awkward but i think that's all it is. He's trying his hardest to fit in and they're just being cowardly, gang mentality pricks to him.
The way the twins in particular speak about him and too him is disgusting and shows their true personalities. Hazel is being vile to him too and i think it's because Dexter sees model types like her all the time in his business and he's hit the nail on the head with her a few times and now she's going on the attack. And a lot of them are just joining in to be in with the larger crowd.......dickheads!
I get the feeling Dexter's just getting more popular with the viewers the longer this go's on though. Let's see how smug they all are when he survives AGAIN this week!