Backhanded Insult
A compliment couched in the form or tone of an insult. Often used by people who *want* to be nice, but fear being seen as weak or disingenuous, but can be unintentional.
When Maurice told Mary she was "the least photogenic pretty chick" he'd ever seen, he meant that pictures didn't do her beauty justice, but it came off as a backhanded insult.