I've been thinking a whole lot lately about the 1-10 pain scales, and how they are objectively dicey because scales that aren't anchored are not useful measurements. My idea of a "5"on my pain scale is, by definition, going to be different than anyone else's - including my doctor, who, being human, may not be able to scrub her version of "5" out of her head before determining a course of treatment.
For a crude and simple analogy of the disconnect, patients are talking in Imperial measurements and the doctors are fluent in Metric. We can both agree that we we're talking about "5", but the difference between 5 mL and 5 oz is... substantial.
Regardless, here is a really good article that dives into the paradox of the measurement of pain. Kudos, John Walsh, for a fine article.