Endangering oneself by sloppy work habits is one problem, but when they endanger workmates, the public or can likely lead to property damage, I cut a wide path around the poor idiot if at all possible.
Back when I was a fourth year apprentice. The NJATC had us attend an OSHA 10 class. During the class we watched a video showing a few real life scenarios. I still remeber some of those images to this day, images of deadly arc flashes and electrocutions. Although this video was extremely graphic, it is a reminder to us just how easily and how close we all can come to an accident if we take safety for granted. The OSHA classes are a great way to break the chain of ignorance that runs in some EC's workforce.