fly-by-night

fly-by-night
    adj 1: (of businesses and businessmen) unscrupulous; "a shady
           operation" [syn: {fly-by-night}, {shady}]
    2: ephemeral; "the symphony is no fly-by-night venture"
    n 1: a debtor who flees to avoid paying
    

47 Moby Thesaurus words for "fly-by-night":
      brittle, capricious, changeable, corruptible, deciduous, dying,
      ephemeral, evanescent, fading, fickle, fleeting, flitting, flying,
      fragile, frail, fugacious, fugitive, impermanent, impetuous,
      impulsive, inconstant, insubstantial, irresponsible, momentary,
      mortal, mutable, nondurable, nonpermanent, passing, perishable,
      short-lived, temporal, temporary, transient, transitive,
      transitory, trustless, undependable, undurable, unenduring,
      unfaithworthy, unreliable, unstable, unsure, untrustworthy,
      untrusty, volatile