You can BS others if you feel you have to, but NEVER BS yourself.
Sage advice indeed. Unfortunately, we may not always be able to help but BS ourselves. Robert Trivers' book "Deceit and Self-Deception: Fooling yourself the better to fool others" offers a pretty fascinating insight as to why self deception is so easy.
As divers we should always strive for honest assessment of our own skills and abilities, but seeking honest peer review is also extremely valuable.