It looks like it's rusted?? And people say it's actually melted plastic? Nope, not buying that.
I've been using various saws for years now, and I've never actually managed to saw through plastic so fast that it's melted with anything except for my Dremel. So unless you're a caffeine-addict hummingbird, you shouldn't have melted plastic at all. And even if you did, I fail to see how it would look like rust... Got any pics to share??
And as for the broken teeth, I'm not surprised at all. The teeth on those things always seemed too flimsy for my liking. Just one of a dozen or so reasons I'd never use one.
For my money,
Zona saws are the best I've found. They're tough, effective, easy to use, and with their ultra thin series, the blade is a mere 0.008" (2/10ths of a millimeter) thick, meaning they don't destroy any more of the model than is absolutely necessary. And for extremely fine work, I love
Hasegawa's Tritool series micro saws. They're made from thin photo-etched steel sheet - not much thicker than a piece of paper. You can actually split the fingers on a Marine's hand apart from one another without destroying the hand with these little gems!