The key is to listen for the "but..."
Sure, everybody hates Pol Pot. But there are plenty of people, when the subject comes up, will always add the "but."
"Pol Pot was a bad person, BUT..."
And then begins the long explanations about how America forced him into power, how it was our fault for going into Vietnam, etc. etc.
To hear a dedicated leftist talk, there is no evil on the planet that, at some point, cannot be eventually laid at the door of the United States. I can come up with numerous examples.