This is a very nebulous statement, and I am not sure exactly what you mean by "proper scientific conduct." To be clear science is about providing explanations of things that are observed. When the explanation is generalized to expand to multiple observations, instances, or circumstances then it becomes a "theory." The validity of the generalized explanation, i.e. theory, is predicated on its ability to explain a broad class of observations, and great weight is placed on a theory that predicts unexpected things that turn out to be true.
Thus, for instance theories of conservation of energy, entropy, the Maxwell equations, and so forth have become accepted theories. The phlogiston theory is no longer accepted as an adequate explanatory fit to observed phenomenon and therefore is discredited.
Anomolies are particularly valued in scientific practice because they provide the means to further validate a theory, modify a theory, restrict the domain of validity of a theory, develop a new theory for an entirely different phenomenon, or develop an expanded theory of greater validity than the original theory.