First off Bondo isn't paint. It is a pasty substance used to fill dents. Yes, thick Bondo can develop cracks and possibly fall out especially if it was applied over rusted areas because the rust continues to get worse. What you are seeing is almost certainly going to get worse.

"The truck didnt have dents in it, but for some reason they used bondo evrry where".

And what do you think the reason might be? For the hell of it? No, the truck has had significant damage, maybe in multiple areas. Bondo, in general, is not a bad thing if it is used properly. If your dad could see obvious spots of Bondo the repair job(s) were not done either properly or professionally. Pass on this one, Eric.

If the bondo is cracking, you're going to have to repatch and repaint the whole car. Your father is right.

hit a good bump and all the bondo will fall off or crack.

do not buy it.

Me and my dad found this extremely nice 81 chevy with a nice limegreen and gray paint job. Except they used bondo every where. I didnt see the truck but my dad did. He said it is already starting to crack and if it cracks anymore its going to ruin the paint and it wont look good anymore. He doesnt want to buy it but I still do. If I keep it will the oaint just crack off and reveal rust? Will ihave to repaint the whole truck? Or what are other options? The truck didnt have dents in it, but for some reason they used bondo evrry where