Beguiling but harmful.

Roget 940: dishonest, dishonorable; unconscientious, unscrupulous; fraudulent etc. 545; knavish; disgraceful etc. (disreputable) 974; wicked etc. 945.    false-hearted, disingenuous; unfair, one-sided; double, double-hearted, double-tongued, double-faced; timeserving^†, crooked, tortuous, insidious, Machiavelian, dark, slippery; fishy; perfidious, treacherous, perjured.    infamous, arrant, foul, base, vile, ignominious, blackguard.    contemptible, unrespectable, abject, mean, shabby, little, paltry, dirty, scurvy, scabby, sneaking, groveling, scrubby, rascally, pettifogging; beneath one.    low-minded, low-thoughted^†; base-minded.    undignified, indign^†; unbecoming, unbeseeming^†, unbefitting; derogatory, degrading; infra dignitatem [Lat.], beneath one's dignity; ungentlemanly, ungentlemanlike; unknightly^†, unchivalric^†, unmanly, unhandsome; recreant, inglorious.    corrupt, venal; debased, mongrel.    faithless, of bad faith, false, unfaithful, disloyal; untrustworthy; trustless, trothless^†; lost to shame, dead to honor; barratrous.    ... show more

Roget 545: deceived etc. v.; deceiving &c.; cunning etc. 702; prestigious^†, prestigiatory^†; deceptive, deceptious^†; deceitful, covinous^†; delusive, delusory; illusive, illusory; elusive, insidious, ad captandum vulgus [Lat.].    untrue etc. 546; mock, sham, make-believe, counterfeit, snide [Slang], pseudo, spurious, supposititious, so-called, pretended, feigned, trumped up, bogus, scamped, fraudulent, tricky, factitious bastard; surreptitious, illegitimate, contraband, adulterated, sophisticated; unsound, rotten at the core; colorable; disguised; meretricious, tinsel, pinchbeck, plated; catchpenny; Brummagem.    artificial, synthetic, ersatz [G.]; simulated etc. 544.    ... show more

Intended to entrap.

Polish: podstępny, lisi, przebiegły

Working or spreading in a hidden and usually injurious way:
— Glaucoma is an insidious disease.

synonyms: pernicious, subtle.

Roget 702: cunning, crafty, artful; skillful etc. 698; subtle, feline, vulpine; cunning as a fox, cunning as a serpent; deep, deep laid; profound; designing, contriving; intriguing etc. v.; strategic, diplomatic, politic, Machiavelian, timeserving^†; artificial; tricky, tricksy^†; wily, sly, slim, insidious, stealthy; underhand etc. (hidden) 528; subdolous^†; deceitful etc. 545; slippery as an eel, evasive etc. 623; crooked; arch, pawky^†, shrewd, acute; sharp, sharp as a tack, sharp as a needle^†; canny, astute, leery, knowing, up to snuff, too clever by half, not to be caught with chaff.    tactful, diplomatic, politic; polite etc. 894.    ... show more