They don't fail that often, but anything that gets that hot and that is made in China now, is more likely to fail than say, the ones made 40 years ago.
And I don't know how the factories mounted them straight to the body panels, but they must have been made differently, because the ones you typically get from the aftermarket will burn the paint right off of any panel you mount it to.
And no matter what, the first time you fire things up don't panic when you see smoke coming out of it.%)
And if you have new paint, don't mount it to a body panel directly. Do what was said and either use a bracket or make a stand-off of some kind. Most just add washers or a spacer to get an air gap behind it so that it does not melt the paint.
Or better yet, if it's an option for your build, get ignition components that don't need a resistor and just run the straight 12v to the ignition and be done with all that resistor/heat stuff.
Paul