show up as
show (someone or something) up as (something)
To reveal someone's or something's true nature, character, or properties. The books shows up the CEO as a megalomaniac only concerned with increasing his own wealth and power. The senator showed the legislation up as an attempt to enrich the nation's wealthiest citizens.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
show someone up as something
to reveal that someone is really something (else). The investigation showed her up as a fraud. The test showed up the candidate as unqualified.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.