I think the key word is 'over'. Like over done, over board, over exposed..., the very definition is that it is not desirable. This comment was telling:
Scott Rao wrote:Some of the brews were lovely: soft and sweet with little hint of overextraction. However, after tasting about 12 batches, it was clear that the brewer was inconsistent... often as much as 10% of the grounds would end up high and dry on the filter wall, the water delivery into the coffee bed was poorly designed for even extraction, and the agitation of the slurry often left the coffee bed quite lumpy during the drawdowns, causing channeling.
This thing sounds like a percolator, but with new water being introduced instead of recirculated coffee water.
I'm not convinced that higher extraction equates to a better flavor experience. Coffee has over 1000 chemical compounds including formaldehyde and arsenic. The good stuff extracts relatively easily, the bad stuff no so much. But if you try hard enough, you can get coffee to taste like turpentine.
I found his closing comment interesting:
One of the most surprising and ironic things about the Expo each year is how difficult it can be to find delicious coffee. I'm not alone in that opinion— at least 20 people echoed that sentiment to me personally this weekend. I tasted plenty of burnt, underdeveloped, and baked coffees on the show floor. Some of them may have been 88+ point coffees, but their roasting and extraction left much to be desired. None of us are perfect, myself included, but we certainly have a long way to go as an industry.
I love that he was 'forced' to use a Chemex.