X & !X can be anything, good or bad. You've just got to pick a value for X that fits in with your desires to get a particular outcome if you want to break it down in terms of good and bad. Got to live to die. The point is that the underlying structure of the argument remains the same whatever you pick.

If you're actually interested in propositional logic, then the suitably named Logic by Paul Tomassi is a very approachable intro to this sort of thing. Though I'm afraid I couldn't say what it goes for these days.