Episode 4, other heroes believe that he was sabotaged in the duel. Start to have understanding towards him and doubt earlier claims. Bar the spear hero.

Vast majority of negativity he receives from people inside the Kingdom is because he is incredibly hostile for no reason. Demanding money. (Episode 7) Plant village, held no prejudice to his being of a shield hero, just know that he was a hero - which he faced with being very rude and defensive. (Episode 10) Soldiers, believing he is a good person, asking to join his squadron.

Only evidence of people generally disliking him are nobles and soldiers (supposedly under the kings commands). Any evidence to show the 'Entire Kingdom' believe he's a racist scumbag?

His stubbornness and paranoia are unwarrantedly indiscriminate. It's not about trust, it's about civility - Naofumi is the embodiment of a 13 year old omega.

Myne is a reason to be paranoid, not a reason to detest people in general.

Once again, it's not about trusting Melty. It's about communicating and not holding initial prejudice, Christ