Oleaginous (adjective)

1. Excessively smooth or slippery, especially from being greasy or soapy.
2. Excessively flattering or insincere in speech or behavior.

Origin:

Early 17th century: from latin oleaginus, from oleum "oil".

Examples:

1. The salesman's oleaginous words left a bad taste in the customer's mouth.
2. Her oleaginous demeanor made it hard for her to be trusted.
3. The food at the restaurant was good, but the table was so oleaginous that the plates kept sliding around.
4. The oleaginous politician promised too much and delivered too little.
5. The movie's soundtrack was ruined by the oleaginous background music.