Originally Posted by headloss

It really depends on the bike. Lower end bikes aren't being properly aligned. I have two disc brake hybrids, a Kona Dew and a Focus Maleta. In both cases, if I seat the axle properly in the drop outs, the wheel isn't perfectly centered. I'm sure I could make adjustments, but I've been hesitant to do so without having frame alignment tools or a proper jig. Better to ensure the wheel is centered than to make sure it sits fully in the dropout imho. In the case of the Focus, the disc caliper was misaligned to an off center wheel and it took me over a year before I realized this and then reset the disc caliper appropriately for the centered-wheel. That's definitely one advantage of a rim-brake, clearances aren't as tight for the braking surface so a slight misalignment isn't as noticeable. It also explains why guys running around on high end frames preach disc brakes like a religion, yet many people have issues on lower level bikes. Level itself being relative, as the Focus had an MSRP of around $1600.