In my 40 years of building and tearing apart engines I've seen a lot of things that are put together poorly. I tore apart a small block 360 one time that was still running and raced (hydraulic cam and sounded like dog-poop till reved up) that had 3 oil galley plugs missing. I tore one apart with the bearing installed with the oil feed hole installed in the cap instead of the block. one had .010 bearing instead of the needed standard size. Engines put together straight from the machine shop without the proper cleaning. ZERO thrust bearing clearance and many others.