shifty

artful, crafty, cunning, devious, foxy, guileful, slick, wily

close, closemouthed, reticent, secretive

clandestine, covert, dark

deceitful, deceiving, deceptive, devious, duplicitous, trickish, tricky, underhand, underhanded

cheating, crooked, defrauding, dishonest, dissembling, double-dealing, knavish, two-faced

lying, mendacious, untrustworthy, untruthful

insidious, perfidious, serpentine, treacherous

unconscionable, unethical, unprincipled, unscrupulous

deceitful, deceiving, deluding, delusive, delusory, false

artful, beguiling, cagey (also cagy), crafty, cunning, foxy, slick, sly, subtle, wily

defrauding, devious, furtive, slippery, sneaking, sneaky, trickish, tricky

insidious, perfidious, treacherous