Even though the encoding of the HDMI cables protects the signal transmissions from the source to the device, which does not automatically mean that the digital signals it carries cannot suffer degradation. According to certain tech websites, the possibility of the electronic data degradation is most likely to occur when the signal has to travel a long distance. However, even in this case, experts say that thanks to the two way signal transmission, there is always a chance that the integrity of the signal is completely recovered, regardless of how much degradation it suffered. As this varies from case to case, you can understand why this is a controversial subject.
If you were to search more information about the HDMI standards, you will find that the recommended minimum operable cable should measure 10 meters or 32 feet. However, on forums and most of the HDMI discussion pages, you will see many customers complaining that the operable distance is much less in practice. The length of the HDMI cable seems to be closely related to the resolution you are aiming for, as in practice the cable is able to transmit a full 1080p signal from a length of over 50 feet.
Considering the problems people had with long HDMI cables in the past, most manufacturers nowadays do not produce cables over 16 feet. However, before you render the HDMI cables useless, you should know that longer cables can have similar efficiencies if you look for ones that have a wider bandwidth. The bandwidth is an indicator of how much information the cable can carry per second. Whilst at the moment the latest versions can withstand a bandwidth over 10.2 Gpbs, it is speculated that the future models will easily reach 16 Gpbs or more.
Overall, when it comes to discussing the efficiency of the HDMI cables, it is important not to make the mistake of thinking that they either work or not, simply because they use digital signals. Sometimes, the signal degradation happens due to inferior cable construction. Therefore, if you are truly aiming for a full HD setup, then you should place the quality criterion in front of the financial one. Quality HDMI cables will not only have better shielding that will reduce interference from other signals, but they will also be made of materials that are more resilient to humidity, heat, direct damage from pets, stepping on them and so on.