Quality issues and their connection with structural aspects of process models have been recently studied, but there is still a notable lack of research into quality aspects of activity labels in business process models. In this paper, we investigate whether the guideline to use verb-object labels actually contributes to improved model quality in terms of less ambiguity and higher usefulness. In an explorative analysis of the activity labels in the SAP Reference Model we identify three labeling styles that differ in the degree of ambiguity they bring about. Based on these styles we design a survey to test the hypothetical connection between labeling style and quality. The results suggest that indeed the verb-object style is superior to other ways of constructing labels. Our findings are deemed to be useful for modeling practice.