The thing with Cameron is that he's not "toxic" in the typical sense, with no obvious scandals, but I wouldn't even consider him "generic" though, he's a pretty mediocre candidate.
Cameron is a good candidate but Beshear is an incumbent here. This is one of the very few races where voters like both candidates and are trying to decide which one they want more. For swing voters its a matter off staying with the guy you know, but they also understand that the challenger here would also be a good governor so there isn't any risk of a wrong choice here.