One of the things that amazes me when I read Shakespeare's plays is the ability of S to create characters representing themselves and not characters representing Shakespeare. While creating a character it does not seem like he ever thought "writing this character will reflect badly on me." The characters are themselves and in his dialogues too it apparent how beautifully he lets the characters speak for themselves. Such people existed in society and the fact that they entered his plays so untarnished by his own likes and dislikes I think is part of Shakespeare's greatness. It is very difficult to do. (I see a bits of GBS in all his characters)
P.S I can well imagine Shakespeare as Shakespeare thinking "I hate this character" but not letting that affect Shakespeare as the character.