We've got a fancy espresso machine in our office kitchen. (It's apparently the kind they used to use at Starbucks stores before they switched over to a more automated "point-and-click" type system.) I was trained on how to use the machine by an old pro, and have been successfully making delicious cups of espresso for a few months.
Lately, my espresso tastes distinctly salty.
I haven't changed the process at all. It has happened on a few separate days, with many other people using the machine, so I doubt it is an issue related to the substance used for cleaning the machine (since I believe that would have been flushed out between my attempts). I haven't heard any other complaints from the 50 (or so) other people who use the same beans, grinder, and espresso machine.
It's a mystery to me, but salty coffee is gross, so it's a mystery that needs solving. (My theory is that I've unwittingly altered my method in some tiny way that I haven't noticed, and that has changed the taste of my espresso. I just don't know what that alteration was!)
Edit: I had a thought: This morning, I made a cup that was salty enough that I didn't want to drink it at all. I poured it out and made another from the other basket on the same machine. It was salty, but drinkable. Potential clue?
'nother edit: Yesterday, my coffee was less salty. The only difference in my method was that I rinsed the basket for way longer than I usually do. It still tasted a little bit off (in the salty direction), but not nearly as bad as previous cups.