paysomeone a left-handed compliment

pay someone a backhanded compliment & paysomeone a left-handed compliment

Fig. to give someone a false compliment that is really an insult or criticism. •

John said that he had never seen me looking better. I think he was paying me a left-handed compliment.

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I'd prefer that someone insulted me directly. I hate it when someone pays me a backhanded compliment—unless it's a joke.