No, just no...
Dark humour is not a bad thing if it's a simple joke and nothing more.
It's especially a thing in more "non-PC" nations. I've laughed at some heavy sh**t, ranging from mild stuff to jokes about prisoners in Nazi Camps, but seeing as a lot of my family died in those same camps, I'm not exactly not disgusted at what actually happened there.
Hell, I even told one of these jokes to my Grandma who was orphaned by the Nazis when she was 4 and she instinctively laughed as well, simply because it was a clever joke.
That being said, there are also people who use "jokes" to disguise things that they actually believe but don't want to say outright.