devious — If you describe someone as devious you do not like them because you think they are dishonest and like to keep things secret, often in a complicated way.
deceptive — If something is deceptive, it encourages you to believe something which is not true.
unreliable — not reliable; not to be relied or depended on.
dishonest — not honest; disposed to lie, cheat, or steal; not worthy of trust or belief: a dishonest person.
fraudulent — characterized by, involving, or proceeding from fraud, as actions, enterprise, methods, or gains: a fraudulent scheme to evade taxes.
fallacious — containing a fallacy; logically unsound: fallacious arguments.
faithless — not adhering to allegiance, promises, vows, or duty: the faithless behavior of Benedict Arnold.
specious — apparently good or right though lacking real merit; superficially pleasing or plausible: specious arguments.
cunning — Someone who is cunning has the ability to achieve things in a clever way, often by deceiving other people.
plausible — having an appearance of truth or reason; seemingly worthy of approval or acceptance; credible; believable: a plausible excuse; a plausible plot.
glib — readily fluent, often thoughtlessly, superficially, or insincerely so: a glib talker; glib answers.
false — not true or correct; erroneous: a false statement.
insincere — not sincere; not honest in the expression of actual feeling; hypocritical.
untrustworthy — deserving of trust or confidence; dependable; reliable: The treasurer was not entirely trustworthy.
