OLEAGINOUS, adj. Oily, smooth, sleek.
Disraeli once described the manner of Bishop Wilberforce as "unctuous, oleaginous, saponaceous." And the good prelate was ever afterward known as Soapy Sam. For every man there is something in the vocabulary that would stick to him like a second skin. His enemies have only to find it.
2009 Update: Having the properties of oil, in particular repulsiveness and indispensibility. Electable.