I'm just as guilty as others of this, but really people, do we think we're not mentioning something when we throw in a comment qualified by "not to mention"?
You'll be reading an argument about the flaws or merits of some system or idea, listing some points that one can stand up for in court. And then a weak but powerful if true argument is sort of slipped under the radar, and this all magically occurs with the phrase "not to mention".
Either mention something and stand up for it, or don't mention it. Doing the "not to mention" shuffle is just a way to say something you don't want to justify in the future. Not to mention, it makes you look silly.