The irony of those ad campaigns is that actual tuna is one of the most delicious things on earth. Tuna from a can is, well, not remotely related in taste and -- to me at least -- disgusting.
Anyway, how about those big TVs?
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.