I don't know about vintage smile but I've heard and been familiar with the concept as long as I've been active in BDSM play (since the late 70's)

The way I look at it is that any pain or discomfort should be deliberate and reflect the will of the Domme, not an accidental, unintended side effect of another activity

Another way that "bad pain" negatively impacts a session for me is that it breaks the fantasy of the Domme being perfect, completely in control and all knowing.