Ive found that either wool programs dont rinse as proper or the lower temperature does something but for me with wool a slight vinegar smell remains in the clothes. Its very minor, my wife really doesnt smell it and she did a couple blind tests on me because she didnt even believe it but i could pick em out every single time. Granted, we've only ever had two washing machines that did this so with that sample size it could be a coincidence (or it could very well just be a fabric property thing i honestly dont know) but i really dont do that anymore.