  Zagarola and Smits developed an empirical velocity parameter for scaling the
outer region of the turbulent boundary layer velocity profile that has been
widely applied to experimental datasets. Plots of the scaled defect profiles
indicate that most datasets display similar-like behavior using the Zagarola
and Smits scaling parameter. In the work herein, it is shown that the common
practice of finding similarity behavior using the defect profile is often
incomplete in the sense that not all of the criteria for similarity have been
checked for compliance. When full compliance is checked, it is found that most
of the datasets which display defect similarity do not satisfy all the criteria
required for similarity. The nature of this contradiction and noncompliance is
described in detail. It is shown that the original datasets used by Zagarola
and Smits display this flawed similarity behavior. Hence, a careful
reassessment of any claims in the literature is required for those groups that
attempted to use the defect profile and the Zagarola and Smits type of velocity
scaling parameter to assert similarity of the velocity profile.
