The paint on our house is peeling badly. It's yellow paint over wood siding (clapboard). When I scrape, I get pieces of paint that are yellow on both sides, and bare wood underneath. Does that mean that the previous owner failed to use primer?
Yep. Or he used cheap primer, or he used the wrong primer, or he used primer made by a different manufacturer. All can lead to paint failures rapidly. I can think of a few application problems (such as applying the paint with a sprayer on a hot surface on a hot day) that could also lead to a failure to bond to the substrate.