I also strongly believe that, when we are dealing with a label that, for better or worse, is viewed as "desirable," people are going to develop a bit of hypochondria when looking at "symptom" lists or behavioral signs of giftedness. Oh yes, that mole does look slightly uneven, I must have cancer! Oh yes, my child is sensitive, she must be gifted! The latter of those two statements I see being very likely among parents who want their children to be something that society views as a positive.
Maybe not an IQ score specifically, but there should be
something else there... early milestones, cognitive precocity, unusual talent or advanced development in a certain area (or areas), etc etc. If there's no LD, there should be
something that shows up on testing. (If there is an LD, I think that test scores should be taken with a grain of salt.)
It's funny because I don't like talking to NT people about it, because then I have to explain why it isn't always desirable.