Premium is much more abused than Brandable imo. There are different variations for Brandable, names that Brand Bucket sells are Brandables, a lot of them Made Up Pronounceables M.U.P.
Then others consider a name like SuperSeats.com which MostWantedDomains.com sold for $48,000.
A generic word not used by its real definition Amazon.com will get the brandable tag.
But yes when someone says Cuoxs.com it is a brandable, well it would be hard to get that brand to sink in with the public. Ease of spelling, memorability are what make a good brand, that little company in Mountain View, California has had some success, I think its pronounced Google. When you reach the status that your name becomes an action like "Just Google it" Then you have made it to the top of the Brand mountain.