It doesn’t debut until next month, but the Fox sitcom “Dads” is already taking heat in early reviews for being crass, sexist and exploiting racial stereotypes. Facing reporters Thursday, its stars and producers defended the show as focusing on human frailties for the sake of laughs and enlightenment. They vowed to refine it, as needed, as the season unfolds, and asked its audience not to rush to judgment. … “Dads” centers on two friends, played by Seth Green and Giovanni Ribisi, whose politically incorrect fathers re-enter their lives and disrupt them. The raucous, loose-lipped dads are played by Martin Mull...