However, did you notice this new setting when importing a DWG in Revit 2013?
If you UNtick the box that says Correct lines that are slightly off axis, then Revit 2013 will bring in the DWG as-is. It won't try to straighten things up to make the DWG more Revit-friendly.
Obviously, use this with care. But for me, 9 times out of 10 I want the DWG to come in EXACTLY as it was drawn.