-What Music Theory Is and Isn't-
There is a common stereotype that guitar players don't know what they are doing. To be honest this is often true, and is mostly due to the often adversarial relationship many players have with music theory. So many players view theory as unnecessary, or at worst something that will suck the "Feel", "Soul", and "Emotion" out of their playing. If you are using theory incorrectly, then yes that can happen. But if you really understand what theory is and isn't, it can be life changing information that will give you control over literally every sound you have ever heard in your life.