not to be trusted; "how extraordinarily slippery a liar the camera is"- James Agee; "they called Reagan the teflon president because mud never stuck to him"
marked by skill in deception; "cunning men often pass for wise"; "deep political machinations"; "a foxy scheme"; "a slick evasive answer"; "sly as a fox"; "tricky Dik"; "a wily old attorney"
If you describe a person as tricky, you mean that they are likely to deceive you or cheat you