Um... There is evil in this world and it is ok to hate evil. No, I’m not talking about Wallace here, but you say it’s not appropriate to spit on ANYONE’S grave. If hitler had a grave, there isn’t anything disgusting enough in my body to lay upon it. He killed a lot of my family, tortured them for months first. Some things trump etiquette.
As a Catholic, it would be my sincere wish that everybody, no matter how evil they were throughout their lives, repented sometime before they took their last breath.
Even a "Lord Have Mercy" between squeezing the trigger and the bullet hitting the brain.
Realistically, I don't believe that most do. But the knowledge of who does and who doesn't is between them and God, not me and God.
Therefore, I cannot say, with certainty, exactly who is in hell and who isn't. That there are people in hell is a certainty. The names and (former) addresses of the residents are not a matter of public knowledge, though.
If I knew, for a certainty, that a specific person was in hell, I would have no problem spitting on his grave. But since I can't say for 100% certainty that a person is, in fact, in hell, I'll hold off on the spit until I get to heaven and have that 100% knowledge.
G_d bless you and Zion!