Pain. How do you compare the meaning of my pain with many people who are afraid of the dentist/are afraid of dental pain itself?

I like Ygrec's idea, that medical helpers would "believe" we are in a lot of pain when they can't "see" it but don't see how that is possible since there's no base or way to compare one person's experience with another. People can literally hurt because they believe they are in pain, have nothing that can be seen to be wrong with them; are they the same as those that are literally in pain but able to "hurt" less because of previous experiences or other, non-medical pain numbing practices? How do you compare the state of my nerves, how "good" they are at registering, how many endings I have, etc. with someone else with a different heritage and background? Why would you not believe me when I say I am in a "lot" of pain? Why? I could be lying, wanting the drugs but what if I'm not lying but your scientific chart or register or whatever decides that the pain I feel is only a 2 when I say it is a 5? How is that different from what happens today? I don't want "scientists" deciding on how I feel or what I want/need!