Deceptive Design, also known as “Dark Patterns”, manipulates users through interface design that exploits cognitive biases, psychology, and design standards to extract money, data, or attention. As governments act against such practices, it is crucial to distinguish them from benevolent design approaches like Persuasive Technology, which aims to influence user behavior positively. By condensing the past decade of Dark Pattern taxonomies with Straussian Grounded Theory (SGT), we have created a set of five heuristics diagnostic of manipulative design. We present the results of a small study using these heuristics and propose that our heuristic evaluation (HE) process can enhance the assessment of Persuasive Technology.