Callow postdocs are often the most caustic, but deadly accurate, observers of the scientific world. A postdoc has to be careful about what he or she says to a senior colleague, but get a few together and pretty soon the real scoop will emerge.
One of my buddies from those days, who is now a well known professor in high energy theory, liked (and likes) to use the term "fraud" to describe other physicists who didn't deserve their positions. So and so is a fraud! Did you see his last paper? Have you ever talked physics with the guy?
Of course, the presence of frauds is inevitable given a random component (sheer luck!) or additional factors (e.g., personal charisma, hype) influencing career success. Below is a figure from an old post on success vs ability. Let the vertical axis be career success and the horizontal axis the ability of the individual. Even if the correlation between the two is as high as .85, we'd still expect to see relatively incompetent individuals in high positions. (Or, equivalently, two individuals of vastly different abilities at the same level of success.) In fact, the correlation between ability and success in academic science is probably anomalously high compared to other fields, with the possible exception of competitive sports.
If you are still unconvinced about the existence of frauds among us, see this research article, as summarized below in the Times magazine. “The Doctor Fox Lecture: A Paradigm of Educational Seduction,” a 1973 article still widely cited by critics of student evaluations, Donald Naftulin, a psychiatrist, and his co-authors asked an actor to give a lecture titled “Mathematical Game Theory as Applied to Physician Education.” The actor was a splendid speaker, his talk filled with witticisms and charming asides — but also with “irrelevant, conflicting and meaningless content.” Taking questions afterward, the silver-haired actor playing “Dr. Myron L. Fox” affably answered questions using “double talk, non sequiturs, neologisms and contradictory statements.” The talk was given three times: twice to audiences of psychiatrists, psychologists and social workers, the last time to graduate students in educational philosophy. In each case, the evaluations by the audience were highly laudatory. To these audiences, Dr. Fox was apparently articulate and intellectual, not a fraud.
Note: the figure is only meant to illustrate the amount of residual scatter present when two variables have a high but not perfect correlation. It does NOT represent any specific data set.