It depends on the model. Some just pull air out. This will preserve the contents short term, about two weeks for wine. Regarding whisk(e)y, it is generally more long lasting than wine but I recently had to dispose of about 4 ounces of Blantons bourbon that I had forgotten about. It had turned milky and did not smell too friendly. This web site http://maltadvocate.com/ is great for all things malted.