I believe that in theory it should have no affect on precision/accuracy.

The issue is when you're dialing your scope in each click will not only move the hairs up/down or left/right but both at the same time.

Ie if you're cross hairs aren't level and you are shooting an 1" low and try to move it up, you may also be moving left or right depending on which direction your cross hairs are tilted.

Tom