Sweetner

Northern Irish / Scottish term Used to describe an outwardly charming but devious artificial and underhanded individual who uses devices of affected charm, flattery or *sweet" facade of one type or another to achieve an aim or goal.

Example-

Gregg - watch him / her, they're a wee sweetner.

Alice - yeah, a wee sweetner - too sweet to be wholesome!
Gregg + aye!