This study aims to gain exploratory insights into how consumers evaluate meat and dairy substitute products (MDSPs). One focus is on the mental shortcuts consumers apply when evaluating the healthiness and sustainability of MDSPs, and a second focus is on how different consumer groups evaluate the similarity of MDSPs to their conventional animal-based reference products (ABRPs). Eight individual interviews with adult consumers and seven with adult non-consumers of MDSPs were conducted in a Western European country to explore how evaluations of MDSPs are formed. Participants who evaluated the healthiness and sustainability of MDSPs used mental shortcuts that are specific to the substitutive framing of MDSPs: the reference halo effect, ambiguity, and dilution. Further, interviewees used the natural-is-better and the familiarity heuristics. Additionally, the degree of processing, ingredient list, and packaging served as cues that triggered mental shortcuts. Regarding the evaluation of similarity between MDSPs and their ABRPs, the similarity of dairy substitutes was rated almost exclusively positively, whereas evaluations of meat substitute similarity varied considerably. Based on the interview data, a preliminary conceptual model with four consumer groups emerged, defined by the dimensions of meat attachment and perceived need for change in the food system. Preserving meat lovers and plant-based diet–oriented individuals evaluate similarity negatively; progressive meat lovers evaluate it positively; and for nondogmatic omnivores, similarity is irrelevant. The present study points to the relevance of considering consumer segments and mental shortcuts when marketing MDSPs. Further research is needed to validate these exploratory findings.