Coffee Appreciation

Big +1 on citric acid - you can buy it for no more than a quid from Turkish shops because they use it in cooking, it's a white powder that comes in a little bag and looks suspiciously like drugs or something a terrorist may possess. Does the job without taint though.

Most things I've read say NO to vinegar for descaling coffee machines.
The ones that are suggested tend to be citric acid based which doesn't taint the machine with vinegar.
Puly stuff isn't supposed to be citric acid either so they've got something funkier.