This study is to show the inadequacy of OT-based analyses of opacity, thus defending rule-based analyses. Analyses in the OT`s framework such as Two-Level Constraints, Sympathy Theory, OO- Correspondence Relation, and Local Conjunction of constraint are found to be inappropriate or costly in solving the problem of opacity in Kyungsang dialect of Korean. Post-Obstruent Tensing applies opaquely in close relation to Consonant Cluster Simplification, where violation marks for the opaque candidate and its transparent counterpart are in a proper subset relation. In such a case, any OT-based analysis suffers theoretical strictures.