Thank you, I have the same issue, it was driving me nuts and I had no idea what was causing it. The thing is, my own drawings look fine, but when I open other people's drawings they look all fuzzy. My anti-aliasing is set to "edges/sketches only" and choosing "none" solves the problem but, as you pointed out, it affects models too. What I'm doing is setting those other people's drawings to "Large Assembly Mode", which solves the issue temporarily (until the drawing is closed and opened again). This is not the ideal solution but at least I don't have to deal with those fuzzy lines.
If someone has a permanent fix for this, I'd be very grateful. I'm using SW 2014 SP 5.0.