The half breeds aren't really shunned in the eragon world people are more afraid of urgals and shades as technically it's almost impossible for a shade to be good but it can happen 

Regardless of their original appearance, Shades become very thin and pale after their transformation. Their eyes and hair became dark red: Their eyes are maroon, "as red as wine" and their hair was crimson, "as red as blood." Shades resembled humans in other ways, with lean bodies "like a runner's, thin and compact."