max is auto triangulating the ngons and creating edges that all go to that bottom right vert. use the create edges tool to manually connect the edges in reasonable ways. also remind me never to import from sketchup!
You could hack another method, throw in an Edit a Vailias said, and setup your smoothing groups for the hard edges, then, a nice Turbo smooth, but with smoothing groups enabled. Not the best solution and might not work, so good luck mate!
my guess would be unwelded vertices... make sure you have converted it to editable poly, go into vertex mode, select all vertices (adjust threshold if needed) and weld...fastest way for this one might just be to re-do the whole damn thing from scratch, it's a mess, LOL sorry man. Looks like you can delete a lot of the…