Update: a regular at my bar taught me to smell my coffee grounds before brewing, and I finally get it
He sat down last Tuesday, watched me scoop the same dark roast I've used for two years, and asked if I ever checked if the bag smelled stale before dumping it in the filter. I tried it the next morning and that batch had a flat, papery smell I'd been drinking for weeks without noticing. Anyone else do a quick sniff test before brewing, or am I late to something obvious?
Started doing this with my tea bags too after a buddy told me the paper dust smell means it sat on a shelf too long. Now I check dates on everything, even the cheap stuff. Weird side effect though, once you smell a fresh batch side by side with a stale one you can never un-smell it. I keep a little jar of good beans just to compare when something tastes off.