I think justified romancized violence (derictly shown or inderictly shown), is much more harmful then a darker, sinister more realistic veiw of violence. If violence is romantizid and justified like it is in the more "tamer" versions of spider man, Robin Hood and King Aurther. It in a sense romantizies and justifies it, giving a greater support of violence as proper response.

Also I never saw the Joker as a Sadist to be emulated but more as a symbol for the corrupting power of fear.