Some comments in another thread about Jack Daniel's got me thinking about this.
I recently attended a presentation about Herradura Tequila. We tasted their Blanco, Reposado and Anjeo expressions. For those who don't know, Blanco (white) or Silver tequila is un-aged, Reposado is aged for less than one year and Anjeo is aged for a year or more. What was interesting was the presenter's point that the difference is one of style, not of quality. It's all the same tequila, after all, therefore the same quality. The aging doesn't make it better, it just makes it different. But it's a difference in style, not quality. The validity of his position is easy to prove. Just taste a Herradura or other premium blanco next to a cheap mixto blanco.
Whiskey is a little different because as aging became more common, virtually no one chose to continue drinking common whiskey (i.e., white dog) and age became a quality measure--six years was better than four, eight was better than six, etc.
But when you get past about ten years, I think the same theory holds. It's not really better quality, it's a different style.
But I'm not sure I've fully wrapped my head around the whole concept. What is the difference between quality and style? It matters because, presumably, quality evaluations should be objective while style preferences are by nature subjective. What do you think?