We were given a test: the same beer (a BrewCult "Hop Zone" IPA) at 1 week old, 5 weeks old and 60 weeks old (we were not told which was which until we guessed the order of freshness) - basically to note how the hop character changes over time (and how much better it is fresh).
The brewer of that beer is advocating drinking beer as soon as possible after it comes out of a fermenter. (I wonder if this applies to the more malt-forward beers?)
I could really see the difference between all 3 samples, and particularly the oldest sample, and particularly when it came to aroma and flavour. Fresher was definitely better!
(as an aside the 5-week old beer also had noticeable diacetyl, so we got a bonus fault tasting of that even though the brewer was quite embarrassed by it).
We were also given another tasting challenge, with 2 Heinekens. 1 was deliberately light struck, 1 not light struck. We were asked which was which. Half the room got it right, and half wrong (including me