I was just looking at this issue on importing AutoCAD to Sketchup and I wanted to find places where there was discontinuity in connecting lines. Well it turns out it looks like sketchup really has a problem with AutoCAD curves, and this seems to be where most of my problems arise. I saw that where straight lines meet a curved arc, the lines almost rarely meet. However I went back and looked at the ACAD file and the line is definitely hitting the curve. I know Sketchup has never been very good with curves so this must be one of the main issues with importing, besides bringing in imprecise ACAD drawings.