Well I have not had mine spontaneously combust but I think there are probably better alternatives. I have quite a few holes where they've burned through and the new ones like I have are fiberglass and itchy.
i have one that i've used a lot over the past few years. few holes, but has held up much better than i ever thought it would. there are definitely better alternatives out there, but for the money it's hard to complain.
i melted mine; but it saved me an expensive cv axle so thats ok
it held up well to the actual splatter, but i got a bit happy on the oxygen and melted it
i've not had mine very long, but i've had a lot of sparks from welding and especially grinding..
i see mine lasting a long time, but mine won't be under molten slag.. so far so good for my method.
i've included a copy of their label for you. i bet they all have the same disclaimer..