Kerry's grades were about the same as Bush's (he's older so wasn't in the same class year at Yale) but the media never used that against Kerry.
Gore, at Harvard, had some A's as I recall, but also had some D's...overall record not much different from Bush's.
None of them were upwardly-mobile first-generation college students from middle-class or poor families...so their attitude towards grades may have reflected their social background.
Gore’s grades were about a C minus. He was a poor student. Bush had better grades than Kerry and Gore.