Another way to inspect a surface that says it has bad trims on it is to select the surface and then run CreateUVCrv - when it asks you to select any additional curves just push enter. That will stick the UV space boundary curves into the Top view, use ZSA (Zoom selected all) to zoom to them. There will be a rectangle for the surface's outer boundary and then all the UV space versions of the trimming boundary inside of that. If some of those looks weird and chaotic like squiggling around or shooting off strangely off the boundary then that's a damaged UV curve, those can be repaired by untrim + retrim.

- Michael