Did the study involve the same testers having double blind(folded) intercourse with large numbers of men from both the test and control group in a controlled environment without being told which was which, after which the hypothesis was tested by sound inference statistics against the primary and secondary errors? Or did they just run around asking random women what they preferred? The latter is not a study, it's just a survey that might help establish a hypothesis to be tested by actual experiments but no reliable results.
Not that such an experimental setup would likely pass the responsible ethics OR STD-concerned medical council.