Does Walder Frey hag a valid complaint that the lords of westeros look down on his house, and was this typical amongst the upper class in the Middle Ages? The feeling I always get is that it’s not so much his house is too low, but that Walder Frey has too many heirs. Would that be a likely reason no ones interested in the Freys, as where is the value of marrying or mentoring a frey

It’s something I associate more with the Early Modern period and the Enlightenment, but snobbery by the old blood against the nouveau noblesse as it were was extremely high. Big part of the reason why Anne Boleyn fell was that the old nobility didn’t like the idea of a knight’s daughter getting above her station; in the ancien regime, the noblesse d’épée despised the noblesse de robe as a bunch of upjumped bourgeois social climbers.

As for why people despise the Freys, it’s a mixture of the fact that the Freys are ambitious and obsequious social climbers, that they’re grasping middlemen who are “toll collectors” and “coin clinkers” (i.e, their money comes from trade not land), there’s the subtext that they enforce their monopoly by burning other people’s bridges and that they tried more than once to conquer the Neck (hence their hatred of the crannogmen), and that they’re disloyal (the Blackfyre Rebellions, Robert’s Rebellion, the War of Five Kings), etc.