I think literally opening is meant (I could be wrong). Not just bacteria getting in is bad, even exposing product to oxygen (and light) is bad for it. Although I don't really believe if you open something just to smell it and don't use it otherwise, and it's stored away, it will go bad just because it was opened for a second. And then, there are some preservatives that have short shelf life, so whatever expiration date is indicated it could mean preservs expire by then...
I don't really pay attention to expiration dates, I use anything as long as there are no changes in consistency/scent/color. I only pay attention to how I store my products, I make sure they are away from light, heat and humidity, and everything is closed tightly. I never leave anything sitting there with a cap or lid off, and when I use something I close it immediately. When it's something in a jar I don't dip my fingers and use a spatula or spoon to get it out, always making sure it's dry; no water ever gets in into anything I use. I have many products that are a few years old, and expiration dates have long gone by, but because I stored them well they are still fine and I am using them with no problems. I have back ups of facial cleanser, cream, some oils and butters, and they are all in the freezer, everything that will have to wait a while until I get to it is there.
Last edited by blulight; 06-26-2012 at 03:26 PM.