So I was making up a 3M pH=5.2 sodium acetate solution and I noticed that it didn't smell right. pH=8.2. This was really weird so I made some up with another bottle of powder. Similar result. Both of these bottles are ancient. A fresh bottle yielded proper acetate.

Recommended shelf life for an opened bottle of -sodium acetate 3H2O- is 1 year. What is it decomposing to? All I know is that it is a base that does not smell quite like vinegar.