Unctuous (adjective)

Excessively or insincerely flattering; oily; smooth.

Origin:

From latin unctuosus, from unguentum ("oil, ointmen.t")

Examples:

1. His unctuous compliments made her uncomfortable.
2. The unctuous sales pitch made her skeptical.
3. The unctuous politician was not trusted by the voters.
4. Her unctuous demeanor was not genuine.
5. The unctuous clergyman's sermons were not well received.