1
general::
Also, backhanded compliment. An insult in the guise of an expression of praise. For example, She said she liked my hair, but it turned out to be a left-handed compliment when she asked how long I'd been dyeing it. This expression uses left-handed in the sense of "questionable or doubtful," a usage dating from about 1600.
American Heritage Idioms
2
general::
Phrase(s): left-handed compliment
Go to backhanded compliment.
McGrawhill's American Idioms And Phrasal Verbs