But within the confines of the gambling skill, I'm thinking more in terms of "knowing what you need to do to effectively influence the odds without getting caught." The wiki says skills should be as general as possible; there's my attempt at being general.

I can totally see the ability to conceal small items developing separately from Gambling knowledge, but I can't see knowing how to cheat at a particular game developing separately from knowing the game. But like I said - that's just my take, and I can completely understand the opposing view.