Epic Paint Failure

So the paint all over the house is bubbling and peeling away in places. What started out as a simple patching project quickly became an overwhelming undertaking of paint scraping, patching with compound, blending, sanding, and repainting. I haven't gotten to the last two steps yet. I'm not sure what the originating problem is that caused all these failures in each room. Was it improper wall prep? Dirty walls? Wet compound? A moisture issue stemming from the crawl space? Latex paint over existing oil paint? Or all of the above? The bathroom's failure is particularly weird, the wall compound underneath is turning to dust and crumbling away. What's up with that?

What a mess!