The most dangerous, in my experience, are the old
steel-jacketed,
epoxy-sealed Sprague "Vitamin Q" caps (not large electrolytics)
sometimes found in miltary equipment. I've got a mark in my ceiling
where that steel jacket embedded itself when the cap blew.
Perhaps you are just having bad luck, but Vitamin Qs are extremely
stable capacitors. Sometimes the seals around the larger ones are a
bit weak, however, and the oil oozes out.
--
Will