Abstract: The number of experiments that investigate the “readability” or “legibility” of texts is very substantial. Literature reviews of these studies appear regularly, and many publications refer to these experiments to suggest evidence for claims. Some of these claims have led to usable recommendations. However, most of these recommendations are often hard to apply and unhelpful. When we are teaching typography, we struggled to explain why the recommendations are difficult to use, why many reviews are uncritical, and why experiments rarely provide reliable evidence to support design decisions. A literature review, guided by experience in both commercial practice and university level education, lead to a list of themes and issues. There are at least 19 reasons why the results of many typographic experiments need to be questioned. This article provides 19 guidelines that could be used to evaluate experimental research into the ways in which texts are read. This list of reasons can be used as a checklist to assess and guide new typographic experiments. We hope to make sure experiments are worthwhile, future reviews are based on reliable sources, and recommendations are effective.