Mudbox does not support faces, polygon, multi, hunky funky junky of a model….
And even if Zbrush does, it does not mean the model is fine and going to look ok when: deformed, subdivided, displaced and rendered. In 3ds max obj exporter will sometimes tell you that there are rats nesting in objects. Sweet. You will find guidelines in mudbox help> import and export>Prepare a model for sculpting *. Although once you import a problematic model the errors will be displayed with nice illustrations as you can see in the image above the post.
In 3ds max, with graphite modeling tools you can select based on criteria and identify problematic areas.
Maya: polygons> Mesh> Clean up… has everything, which still does not mean you don’t have to go in and fix all the small errors manually. It helps me relax. Non-manifold geometry option will fix more serious errors, while other options will help you find errors in topology. Keep calm.
And what are non manifold polygons exactly: