Like many, you think you can tell whether a screen actor who acted in a few movies you liked and whom you didn't know personally was a good man.
Consider what you're saying...you've never met him either and don't know any more about him than I do. And yet you can pronounce judgements about what a bad person he was and how he deserves to be mocked and ridiculed after death. Pretty classy.
No, I certainly don't know him personally but what I do know is that he participated in gay culture with a very high-profile movie, was a drug addict, and left a child without a father.
Not good fruit. Now, I don't know that he was a bad man, but those are bad things. Certainly not deserving of respect.
And don't think that Ledger necessarily was good because he gave to charity. Almost all Hollywood celebrities give money to charities. That doesn't necessarily make them good because many of those charities have political agendas and are the opposite of good. Can't say about the ones he gave to because don't know what they were but I would not automatically believe them to be healthy ones.