Context: Dark patterns are user interface or other software designs that deceive or manipulate users to do things they would not otherwise do. Even though dark patterns have been under active research for a long time, including particularly in computer science but recently also in other fields such as law, systematic applied ethical assessments have generally received only a little attention. Objective: The present work evaluates ethical concerns in dark patterns and their research in software engineering and closely associated disciplines. The evaluation is extended to cover not only dark patterns themselves but also the research ethics and applied ethics involved in studying, developing, and deploying them. Method: A scenario analysis is used to evaluate six theoretical dark pattern scenarios. The ethical evaluation is carried out by focusing on the three main branches of normative ethics; utilitarianism, deontology, and virtue ethics. In terms of deontology, the evaluation is framed and restricted to the laws enacted in the European Union. Results: The evaluation results indicate that dark patterns are not universally morally bad. That said, numerous ethical issues with practical relevance are demonstrated and elaborated. Some of these may have societal consequences. Conclusion: Dark patterns are ethically problematic but not always. Therefore, ethical assessments are necessary. The two main theoretical concepts behind dark patterns, deception and manipulation, lead to various issues also in research ethics. It can be recommended that dark patterns should be evaluated on case-by-case basis, considering all of the three main branches of normative ethics in an evaluation. Analogous points apply to legal evaluations, especially when considering that the real or perceived harms caused by dark patterns cover both material and non-material harms to natural persons.