Packaging can attract consumers’ attention and purchase on the shelf space. Therefore, many manufacturers use large packages to occupy shelf space and attract consumers. However, consumers often find that the compartments or air in the package occupy a considerable amount of space after opening the package. These spaces are called slack fillings. This study suggests that how consumers evaluate slack filling is related to consumer persuasion knowledge and how packaging is presented. This study uses two experiments to explore the interaction between the package presentation types (quantity labeling outside the package and the arrangement inside the package) and consumer persuasion knowledge. The results of two experiments found that consumers with low persuasion knowledge are not sensitive to how packaging is presented. Those with high persuasion knowledge are more concerned about the manufacturer’s marketing methods, but when there is a clear quantity label on the outside of the package or the packaging is presented in a uniform arrangement, both ways can increase consumers’ perceived appropriateness for the packages. This study suggests that manufacturers should maintain the appropriateness of packaging, and avoid consumers from negatively evaluating products due to slack filling packages.