An even bigger challenge for me is when the AC inlet is on the side of the component, for me that looks odd and I don't care for it.
Power Cord Placement
Imagine the back panel of a high quality power amplifier or preamp. Where's the inlet socket for the power cord? Sometimes it's to the far left, sometimes to the far right, but what really annoys me is when the inlet is right in the middle. I cannot think of a more difficult location when it comes to distancing power cables from audio cables. It makes want to consider battery powered equipment!