Here's another example of why you need to unplug your iron when you aren't using it. One day last summer I began to notice what seemed like an electrical burning smell. My first thought was that it was a problem with the new air conditioning unit we had just installed. I walked through the house and couldn't see anything - then walked around the outside of the house - nothing. When I came in the house there was a definite haze to the air. Still couldn't determine where the problem was - so I called my husband to come home from an errand. By the time he arrived, there was a marked haze and the smoke detector was going off. He told me to call the fire department and get outside. He looked through the house and found the problem! It was my iron in the back sewing room. I hadn't looked there because I knew I hadn't been in that room for two days. He called to me to bring a pan and he grabbed a pot holder. We got the iron outside before the fire department arrived. It had burned a hole through the layers of ironing board cover. I believe we were just minutes away from a full blown fire.
The next day I emailed Black and Decker and they called me back. I explained the problem and they sent me a new iron. They said they wanted the iron to be mailed to their quality control department and they would send me a mailing label. When I finally got a note from them - they only wanted the end of the plug which has a code stamped in the plug.
Needless to say - I now unplug my iron each time I am done using it. On the one that burned, I always turned it off when done, even through it was an auto-off - but never unplugged it. Much, much better safe than sorry! I'm just thankful I was home when this occurred.
When you look at the pictures, the chunk that looks like a silver stone is the metal that melted out of the iron. This was a Black and Decker Digital Advantage iron that I had used for several years with no problem.