As always, you have put your finger on the point very precisely:
It is relatively uncommon, it comes from years of experience and personal contact with, in this instance, the fishes and the actual measurements. Not just the hobbyist that "thinks" that these fishes are different, but those scientists that have done actual measurements themselves and therefore know what to look for, so we are talking about persons such as Kullander that have done very little else than study these fishes all their lives long. Someone that has just started studying these fishes, even a Ph D student that has studied such fishes, just simply does not have the experience to be able to have this knowledge. What I am also very wary about are the new generation molecular biologists or persons that do the DNA sequence determinations who all of a sudden decide that the previous morphological assessments can now be replaced by DNA sequences, this is just not good enough. I maintain that scientists that wants to lay claim to have such "intimate knowledge" are only those that have gone into the field and have developed a feel for the critters and the environment in which the critters occur.How common is it for the specialists in techniques, to have their own intimate knowledge of the critters themselves, though ?
On this point, my comment is a categorical "NO", you need to have that specialist knowledge that you have just referred to before and that is something very special.and if it all boils down to gut feelings and subjective "feelings", we'd be better off just taking polls.
These are very valid points that you have made here, Dave, thanks for making them.