Sentences with negated adjectives receive a stronger interpretation than given by their semantics, a phenomenon called negative strengthening. It has been reported that inherently positive adjectives display a higher degree of negative strengthening than inherently negative adjectives. We investigate two possible causes of this asymmetry: intrinsic adjectival polarity and face considerations. Results of an experiment where face-related factors were manipulated suggest that both polarity and face contribute to the asymmetry. Extending a probabilistic RSA model of polite speech, we formalize the listener's reasoning about a speaker's use of negated adjectives as a tradeoff between expecting a speaker to maximize both an utterance's social and informational utility, while avoiding inherently costly adjectives.