ISPE’s Cleaning Validation Principles course provides details on how to formulate sound scientific rationales and to maintain them. Through practical industry examples, we discuss pitfalls in cleaning validation approaches. We discuss limit setting in multi-product environments and how to sample and test for residues using compliant analytical methods. The challenges that are faced with establishing programs that suit both automated and manual cleaning are addressed, as well as how to establish cleaning programs for challenging environments, such as development.