Within the scope of the uniqueness problem, the scientific credibility of the starspot hypothesis is examined. According to the two analyzing criticisms in this study (general and specific approaches), the starspot hypothesis is a consistent physical problem. That is, there is no uniqueness problem which discredits the starspot hypothesis. Confusions among the different meanings of the word "uniqueness'' act as a prime source of the ambiguities. Nevertheless, the empirical evidences implying non-uniqueness of spot solutions, such as indeterminacy of spot latitudes, and therefore latitude fixing, and dissimilar solutions of models, are actually caused by insufficient accuracy of observational data not because of an intrinsic problem of uniqueness. Therefore, the starspot hypothesis must be attributed at least the same level credibility as the other light curve analyzing techniques of eclipsing binaries or cepheids since non-uniqueness because of observational data with limited accuracy is also a problem for them. Studies proving unique spot effects on the light curves and on the line profiles are reviewed. Confusing comments and misleading statements about the uniqueness problem in some leading literature are criticized. (C) 1999 Elsevier Science B.V. All rights reserved.