Nobody mentioned invoices !
My colleagues are forever leaving scrap lying around with the good stuff. Trouble is you can't tell some bad parts till you fit them, and if you fit an intermittent problem in you can end up with a lot of head scratching. There is NO excuse for not keeping your workplace in a semblence of order. In fact most of the muppets ask the rest of us for parts as they can't trust what's near them. Just bin it or make them evaluate it.
As for breakdown... If someone can't do their job it ain't my problem. One warning then take action. I don't care beyond that and certainly wouldn't lose sleep over confronting anyone about it. Stop covering up for the lazy gits and get them off their butts now!