Sentence:  The threat the most radical of them pose is evidently far greater at home than abroad: in one characteristically <WSD>slick</WSD> and chilling Isis video – entitled “a message to the Jordanian tyrant” – a smiling, long-haired young man in black pats the explosive belt round his waist as he burns his passport and his fellow fighters praise the memory of Zarqawi, who was killed in Iraq in 2006. 
Meaning of the word marked with <WSD> tags:  Superficially convincing but actually untrustworthy.