I_am_the_smartest - accidentals as you call them, may not be so accidental. Listen to a Robben Ford lick in a standard blues lead - he'll throw all sorts of notes in there - he's amazing. Blues with a jazz flair. Jazz is based on these "accidental" improvs - that's the whole idea - "what can I play here that sounds cool"...going against the "normal" lead/scale progressions.