We have two irons. The first one got a little funky when I tried an iron-on project and scorched some fragile elastic. My husband, the one who actually presses clothing regularly, bought a new iron just for regular clothes. We kept the old iron for projects so I wouldn't junk up a new iron with accidents.
I'm trying to follow directions and do things right in my old age, so I always test new fabrics on my sewing machine and with the project iron, particularly if they're not some poly-cotton blend. I pressed most of my latest project dress with a pressing cloth and the project iron, but the bust darts needed more attention. I tested the project iron directly on some spare fabric and it was fine at a low setting. I then ironed the center back seam to prepare for the zipper, and three of the four bust darts. All was fine until I hit one of the darts a second time and the iron made a couple tiny holes in the fabric. Either the iron got too hot or the surface snagged the taffeta. Whatever happened, I spent some time removing the front bodice piece this morning. Looks like I'll be cutting a new bodice front in the next few days. Good thing I'm not on a deadline.
The lesson here is to always test your fabric, keep a project iron on hand, and make sure the surface of that project iron isn't so scratchy that it will snag your fabric. Also order extra fabric when you buy online.