Can we all just take a moment to appreciate how hung up the guy is on this? He took issue with the woman thinking it at the hotel desk, and he still takes issue with it now. It’s like, 10 minutes later, they’ve been shown to their rooms and they’ve been talking before this; he brings it up out of the blue. Sam doesn’t give a shit, he just either corrects people who mistake them or leaves it, then forgets about it. It plays on Dean’s mind. He is really defensive about it - ‘what do you mean, we look like the type?’ is what he said to the hotel owner. Like, chill the fuck out, why do you care? Because he is overcompensating. Look at his reaction when Sam says it - you can’t see it in the last gif because it cuts off too fast, but his face falls, and he’s looking at the floor and he is not smiling. Sam is comfortable enough in his sexuality to be mistaken for gay and not care, but Dean is not, and he doesn’t like it when people think he’s not straight, and what he likes even less is people noticing this.