Historians like nothing better than to debunk other historians, so there are plenty of papers shooting down one myth or another. I enjoy these papers as much as the next person, but sometimes the debunking becomes the new myth. So, if I may turn the question round a bit, here is a case where I think the original "myth" has merit, and I'm not convinced by the "debunking".
"Myth". The ancient Mesopotamians who compiled Plimpton 322 were looking for Pythagorean triples and had a powerful method for finding them. For example, they found the triple (13500,12709,18541).
"Debunking". By Eleanor Robson in Historia Mathematica 28 (2001) 167-206, which may be viewed here.
