Responses
I agree. Skyler received so much from Yeonduk yet it took his mom so little to convince Skyler that Yeonduk was a bad guy. I'm really frustrated at Skyler's selective memory and attention. It's like deeo down he wanted to give his mom at least the satisfaction of being right, by acting like such an asswipe... #-.-)

Of course I know that his wrongs rank lower than his mom and Yeonduk's but when you look at what Skylar knows about Yeonduk's definite actions, it doesn't make sense that he would have built Yeonduk up to be the villain that he did.
He thinks Yeonduk is a snitch to stay on his mom's good side but Yeonduk never said anything about him smoking, hanging with bullies, ditching him to go drink and spend money where he wasn't supposed to. If he were really a snitch, Skylar would have been on a much shorter leash and he has to know that.
He thought Yeonduk was just being nice for appearances but Yeonduk gave him presents in private. Yeonduk helped him make an event for his gf. Yeonduk watches his little brother when HE is supposed to do it. Yeonduk even got mad at him on behalf of his little brother, got hit over it and didn't say a word.
The truth is that Skylar knows that Yeonduk isn't what he wants him to be but he needed a scapegoat because his mom is terrible and Yeonduk was an easy target. He used the fact that Yeonduk wouldn't say anything as a round about justification. "Well of course he won't say anything. He's on moms payroll". He could have confirmed his thoughts at anytime but he didn't WANT Yeonduk to be innocent because then it would be like he was a bad guy.