Vinsmoke king is probably a really bad person because I don''t think Sanji hating him so much could be the result of a misunderstand, but we don't know the character much yet to tell if he's a "complete bastard" or not... at least I thought he would be an abusive father and he doesn't seem to be so horrible with his sons...
misunderstanding*
Well he seems to have an ego about murdering people by that portrait thus the title of "complete bastard". Besides Sanji clearly hates his family. My theory is that it could be about his mother.
Bastard please! Sanji's gonna kick you around the ground!
Btw Sanji's (Father) isn't really what I expected but one thing I was right about, is that HE"S A COMPLETE BASTARD!
I like Sanji's sister though, she's funny.