Following up on Hyperbole and a Half's critique of the Wong-Baker Scale, xkcd weighs in on anchors of common assessment scales.
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His mouseover caption presses the point: "If it were a two or above, I couldn't answer because it would mean a pause in the screaming."
This reminds me of a conversation with a friend about the pragmatics of rating the pain which brought you to the doctor's office. Our consensus: Rating the pain a 6 is high enough that the doctor will take you seriously, but not so high that they think you're lying or make the wrong diagnosis.