The goal of this study is to provide better empirical insight into the licensing conditions of a large set of NPIs in German so that they can be used as reliable diagnostics in future research on negation-related phenomena. Experiment 1 tests the acceptability of 60 NPIs under semantic operators that are expected to license superstrong, strong, weak, and nonveridicality-licensed NPIs, respectively: antimorphic (not), anti-additive (no), downward entailing (hardly), nonveridical (maybe, question). Controls were positive assertions. Cluster analysis revealed seven clusters of NPIs, some of which confirm the licensing categorization from the literature (superstrong and weak NPIs). Other clusters show unclear patterns (overall high or medium ratings) and require further scrutiny in future research. One cluster showed high acceptability ratings only with the antimorphic and the question operator. Experiment 2 tested whether the source of this unexpected distribution was a rhetorical interpretation of the questions. Results suggest that rhetoricity was not the sole source. Overall, the results show gradual rather than categorical differences in acceptability, with higher acceptability corresponding to stronger negativity. The paper provides the detailed results for the individual NPIs as a preliminary normed acceptability index.