I get all that, I just thought Sam could have been nicer about it, although we also know from earlier episodes that Dean enjoys reading, so it's not a stretch to assume he does have "book smarts" although more toward the libral arts than science and mathematic variety. But yeah, he's absolutely street smart - and Sam is as well. I don't think one thing excludes the other, but Dean sees it that way, and though it's only meant in fun, Sam certainly doesn't help when he makes what he thinks are throwaway comments.