Durability issues aside, any HDMI cable of a given spec (e.g., "1.3") should be as functional as any other cable of that spec: the HDMI specs stipulate the minimum required signal quality, so if a cable doesn't meet those req's, it can't (legitimately) be sold as "HDMI"; and if it does meet them, the signal should be loss-less for your equipment.
For different -lengths- of HDMI cable, different components may be required to meet that minimum std, but the label guarantees the end-to-end signal quality.
Over time, HDMI standards have evolved: an "HDMI 1.1" cable may lack the necessary bandwidth for "HDMI 1.3" equipment. But, there's no appreciable price difference, so buy the latest (1.3a) standard and you're safe (as the cables are all backwards compatible).
Again, any $12 "HDMI 1.3a" cable should provide as good a signal as your HDTV equipment can use.
If your requirements exceed HDTV standards, there's a "Category 2" HDMI spec (HDMI 1.3b?), but it'll be a few weeks before any of us need a signal richer than 1080P, I suspect.
But... sure, keep the economy going by buying Monster cables. I listened to a BB salesjerk telling a couple that "I don't use anything but Monster Screen Cleaning kits" [$25!!]. My impression is that the Monster prices are just another tax on ignorance.
mshan & Crusty: Only a -FAILED- HDMI cable will contribute signal degradation. Period. A failed cable's not an impossible event. Nor is it impossible that devices' drivers/receivers may be out of spec and result in data loss, nor that the s/w passing the data-stream may have defects. But a cable meeting the HDMI spec should deliver its stipulated "noiseless" signal -- i.e., a signal whose losses/noise are below the threshold required to defy loss-less digital reconstruction.