Get some whole freshly roasted coffee beans, put one half in the freezer, and grind the other half and let them sit in an open container for two weeks. At the end of the two weeks, grind the beans that were sitting in the freezer. Now brew both sets of beans and do a blind tasting.

You’ll be able to tell the difference, your coffee-drinker friends will be able to tell the difference, fans of instant coffee will be able to tell the difference, and if you have access to a chemistry lab, their mass spectrometers will definitely be able to tell the difference.

It’s completely different from gold-plated audio cables, where you can take very precise measurements and prove categorically that they have no effect.

Also includes the hilarious "white wine with food colouring" test -

"In one test, Brochet included fifty-four wine experts and asked them to give their impressions of what looked like two glasses of red and white wine. The wines were actually the same white wine, one of which had been tinted red with food coloring. But that didn’t stop the experts from describing the “red” wine in language typically used to describe red wines."

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I dabble with fancy coffee now that I've got a few solid shops on my commute to work (the rest of the times I'm stopping at Dunkin Donuts, lest you think I'm more of a snob than I think) and my own personal policy is that for whatever variable X is involved that I'll only continue with X as long as I can tell a noticeable & pleasant difference. So for instance, I'll only get pourovers at places where I notice a difference between that and the standard (which implies quality of technique, according to the coffeenistas), or whatever beans they're using for a pourover if my reaction is "meh" I'll not get it again but other times I'll get it multiple times a day until they run out.

Agreed that this is all anecdotal and not double blind, and agreed that short of nuking things from orbit that double blind is the only way to be sure. However, as someone with very little skin in this game other than sometimes I want something better than Dunks, I can tell you that some variables matter to me and some don't.

I'm not sure if that is entirely comparable to what I meant. I am not claiming freshly grounds tastes better or has some other pretty subjective property. My claim is rather that I believe when doing an experiment where you'd for instance take a couple of pre-ground coffees and one fresh ground one that people would pick out that one as being different. Whether they like it more is up to them. With much more likelyhood than being able to pick out expensive wine out of a set of mediocre wines or so. Again, I believe solely for the reason that the freshly ground I drink has a completely different taste from all other pre-ground ones I drank in the last years. So yes you have a point in calling that subjective :]