Finally somebody caught dean out for his lying
This was a really interesting little scene. Personally, if Dean was lying it wasn’t about wanting to avoid research. It was about Cas. From the beginning during the phone call, Dean immediately gets up and moves away from the table, apparently to keep his conversation with Cas private from Sam and Kevin. He’s obviously concerned about Cas because his very first question is “How are you?” After Cas gives him the case info, he says, “How you want to work this, I check the scene and then I’ll come pick you up—”
He takes it for granted that he and Cas will meet up and he doesn’t ask even ONE question about the ‘case’. His only questions are about Cas—first “How are you?” and then about meeting and then asks about Cas again (Are you sure that you’re—) when Cas hangs up.
We see him a short time later, in the same clothes with a small duffle, leaving, while Kevin and Sam look confused. Probably within 30 minutes of that phone call, Dean is on the road.
He quite purposefully makes it plain to Sam (and Zeke) that he WILL NOT be seeing Cas when we know from what he said on the phone and his later actions, that finding Cas is one of his main motivations. He downplays anything about the case to prevent Sam from coming along, because if Sam did then Dean would have to stay away from Cas. Plus, he really doesn’t have much info to give since he spent all his time on the phone asking Cas about himself.
Dean leaps like a shot to go on this case because Cas.
Then when Kevin says this, he deliberately says ‘You got me.” In other words, he’d rather they think he’s ditching them because he can’t stand research than for them to know the truth—that he’s determined to find Cas and Sam cannot come along because Zeke can’t meet Cas.
"I’m just gonna go on a little look-see." Drive 1000 miles on a ‘look-see’. To avoid research. Sure. Not because Cas.