Technically a brand name, it has come to discribe any type of plastic body filler used for automotive body repair. Moslty talc, and is mixed with cream hardener for it to dry.
Always dries faster than you want it to, especially in hot & dry weather. But once you can work with it, that's no problem, it actualy saves time in the body shop.
There is no shame in using it when using it correctly. In a body shop, it should be no more than 1/8 inch thick. It's the redneck
morons who slap 12 gallons of it right over paint and rust, then spend as mucn time as it would have taken to do it right to sculpt the shit with an artist's touch to mimic the appearance of actual bodywork. But bondo not put on correctly will not last forever, and this crap bodywork will eventually crack and fall off and make whatever sucker baught the car want to scream and gouge his own eyes out.
-"Aww man, my quarter is all dented and rusted."
--"You should rough out the damage, use dent pullers if neccisary, and shrink any stretch areas. Also construct some patch panels out of the same gauge material and weld it in place of the rusted areas, after cutting it out, of course. Then grind down the welds, grind off the paint and primer, and then spread the Bondo."
-"Umm, that sounds like it would require effort. I'd rather be inside touching myself. i'll just throw this gallon can of Bondo on it. That'll work."
--"I'm gonna go over there now..."