The HDMI standard is particularly prone to jitter, so the sound has the potential to vary more than for SPDIF cables. I find that the picture varies significantly as well. The Wireworld HDMI cables are the best I've tried -- significantly better than 2 Belden based Bluejeans and numerous cheapies I've tried. I'd imagine that the same technical factors which allow digital cables to sound differently, apply to HDMI. Among these would be a variance on edge triggering. If you really want to get tweaky, you can apply mechanical damping and RFI damping to your HDMI cables.
Here is a survey of reviews discussing differences.
http://www.whathifi.com/reviews/accessories/hdmi-and-video-cables
Here is a survey of reviews discussing differences.
http://www.whathifi.com/reviews/accessories/hdmi-and-video-cables