Is Jabba bad? I mean Han did owe him money and Han had the reward and time to pay him back but never did. I love Han but its not really Jabba's fault yet a Jedi tried to pull a gun on him. I guess he is bad for keeping the droids. I mean Luke trained them for Han but he keep them. And he did keep Leia chained up but she did try to steal from him.
Anybody that keeps a giant ugly moster in his basement and feeds people to it when they don't obey him is probably an evil person.
I guess that depend of your perception of bad. Jabba is a member of the Hutt's clan. It's sort of organized crime and all about business. The thing about Han is that he worked for years for Jabba and he was held in high esteem by him for he is a very good pilote and was a reliable employee. But the incident with the Empire and the loss of the merchandise put Han into trouble with Jabba and the Hutt's Clan. As is refered in A New Hope. For more informations on that matter you can go toward the EU and read The Han Solo trilogy.
FirstStarWars - As for wheter or not Jabba is bad you seem to have forgotten some fact here: How can you consider yourself a good person, when you're feeding your rancor with Twi'lek slaves for fun? When you execute prisonners without due process by mean of a saarlac' mouth? All in Jabba's life may be linked to business, power and influence but he his clearly wicked.