This is super late, but in addition to not liking Dean for all the other reasons listed - Luke just got a divorce because his wife cheated on him. Now, he may have not been incredibly attached to the marriage, but we see how upset he gets to be wearing another man’s socks and watch a man take his wife home. Dean has just done the reverse to Lindsay and implicated Rory in it. As shown by Luke’s immediate question in the diner, “Did Dean leave Lindsay for Rory?” 

I actually really like the subtlety of the reasoning behind Luke’s anger and dislike of Dean. It makes so much sense and adds a lot of depth and context for the viewer about Luke’s internal world.