amoral, artful, astute, back door, backstairs, calculating, chiseling, clandestine, corrupt, covert, crafty, criminal, crooked, cunning, dark, deceitful, devious, dishonest, dishonorable, doubtful, dubious, evasive, false, falsehearted, feline, felonious, fishy, fraudulent, furtive, guileful, hugger-mugger, hypocritical, ill-gotten, immoral, indirect, insidious, not kosher, privy, questionable, quiet, rotten, scheming, secret, shady, shameless, sharp, shifty, sinister, skulking, slinky, slippery, sly, sneaking, sneaky, stealthy, surreptitious, suspicious, treacherous, tricky, two-faced, unconscientious, unconscionable, undercover, underground, underhanded, unethical, unobtrusive, unprincipled, unsavory, unscrupulous, wily