When Visio 2013 first came out in early 2013 we noticed a bug where inserted AutoCAD files did not display at the full resolution and looked blurry at high zoom levels. We documented the issue in the D-Tools support wiki and I notified my contacts within the Visio division at Microsoft. After a couple of emails Microsoft said that they would fix this issue in the Visio 2013 Service Pack 1, due in March 2013.
I am pleased to announce that this fix has been implemented by Microsoft and SP1 is available for download at the following link. http://support.microsoft.com/kb/2817443
I was going to do a full review on this topic but VisGuy Chris Roth beat me to it. This article tells you everything you need to know about this specific problem and solution. http://www.visguy.com/2014/02/28/visio-2013-cad-import-fixed-with-sp1/
Here is a CAD file in Visio before SP1
Same file after SP1
Problem solved. Thank you Visio division of Microsoft for getting this taken care of. It means a lot to all of the users that rely on AutoCAD compatibility to do their jobs.