Not really, I have 2 $12 25 foot hdmi cable that work just great. I bought the cheapest one I could find because, hey, if it doesn't work I'm only out $12. But it's been working great for a couple years now.

Unless you are making your own cables, I don't see why.

If the >6 feet cheap cable you bought doesn't work properly then it is faulty and you can get a refund.

"The real time to worry about the quality of those cables is when you go over 6 feet," would make sense as something said to the cable manufacturer. Translated to consumer-speak, that would be "it's really quite hard to find cheap HDMI cables longer than 6 feet from a well-known brand." (Of course, shady brands will just sell the crappy cables and rely on people's innate laziness and stores with no-refunds policies.)