The problem when you buy really cheap cables is that they don't have the shielding that the more expensive cables have, and at these speeds, and the amount of data flying around, shielding is very important. Well, plus is the amount of twists and number of individual wires making up the individual part of the cables. Usually the jacket is thicker, but I definitely understand the 'buy cheap cables' meme. I can order those cables through distribution, and even with the premium that we pay over high volume purchasers, the markup for us to sell at those prices is in some cases as much as 300%, or more!
Heck, we were buying the expensive Belkin gold IEEE 1394 cables for 20%, or less, than Best Buy prices at the time... It's a general ripoff, but when you are contemplating saving a few bucks on an HDMI cable that carries both video and audio, and you will be watching this for hours a day with your wife and family complaining about the crappy signal, you look for items on sale or find other means to get better cables.
HDMI isn't like the old tyme speaker wire... It's got to be able to push a lot of data, and increasing speeds. I've gotten good service with the lower grade Monster Cables where the markup isn't stratospheric like the big-dollar ones. Actually one of the cables I rely on is from the Apple Store, on sale...
But anyway...
----------
One thing is to make sure that the cable plugs in all the way solidly. I had a blue ray player that wasn't so great for output, but after unplugging the cables and plugging them in again found that the cable didn't quite engage properly. After reseating them, things were much better... I had an AppleTV that had issues with out wired network. It was the rubber no-snag bit that hung up on the case of the ATV, once I jiggled that, everything was fine...