I only ever got an RC to actually spark lucidity once, and that was when I first started LDing. It was very definitely an automatic response to do a nose pinch (affirmation in WL), which failed (I could breathe), and THEN I became lucid, with no inkling of lucidity before. But that was the only time. Since then I have always become aware first, then done an RC to confirm.
On several occasions I have found the nose pinch RC to fail (I could not breathe), but was convinced I was dreaming. On a few occasions I have perservered with the node pinch and it workked on the second or third attempt.
I now usually look at my hands and count the fingers (if there are any!). Often my hands are all wavy, have more digits, or on one occasion it was see-through.