beguiling

astute, facile, glib, sharp

crooked, deceitful, deceptive, dishonest, fraudulent, insinuating, knavish, Machiavellian, oblique, serpentine, shady, shifty, slippery, sneaky, treacherous, underhand, underhanded, unscrupulous

backhanded, double-dealing, hypocritical, insincere, left-handed, mealy, mealymouthed, smooth-tongued, two-faced

circuitous, circular, roundabout

clandestine, concealed, covert, furtive, hugger-mugger, secret, stealthy, surreptitious, undercover

calculating, plotting

artful, crafty, cunning, devious, foxy, guileful, shady, shifty, slick, sly, sneaking, sneaky, subtile, subtle, trick, trickish, tricky, underhand, underhanded, wily

crooked, defrauding, dishonest, dissembling, double-dealing, duplicitous, faithless, fast, fraudulent, knavish, lying, mendacious, untrustworthy, untruthful

bogus, counterfeit, fake, feigned, forged, phony (also phoney), sham, spurious

insidious, perfidious, treacherous

artificial, backhanded, hypocritical, insincere, left-handed, two-faced