glib

Having a ready flow of words but lacking thought or understanding; superficial; shallow.

A much more thorough examination of this period is essential, and no glib answers should be accepted as good coin.

Smooth or slippery.

a sheet of glib ice

Artfully persuasive but insincere in nature; smooth-talking, honey-tongued, silver-tongued.

a glib tongue; a glib speech

I want that glib and oily art, / To speak and purpose not.

Snarky or unserious in a disrespectful way.

Its style is both open and arch, never verging on glib camp but always a little removed, reducing large emotions to small observations and thereby making them all the more effective.

When Mr. Franco called Mr. McCarthy and asked why he had written a book about such a repellent character, he was glib. "He said, verbatim, 'I don't know, James, probably some dumb-ass reason,'" Mr. Franco recalled.

To make smooth or slippery.

1628, Joseph Hal, “Christian Liberty Laid Forth,” in The Works of the Right Reverend Father in God, Joseph Hall, D.D., Volume V, London: Williams & Smith, 1808, p. 366, https://books.google.ca/books?id=8iUBAAAAQAAJ&printsec=frontcover#v=onepage&q&f=false There is a drunken liberty of the Tongue; which, being once glibbed with intoxicating liquor, runs wild through heaven and earth; and spares neither him that is God above, nor those which are called gods on earth.

And, when to all his Angels he propos'd / To draw the proud king Ahab into fraud, / That he might fall in Ramoth, they demurring, / I undertook that office, and the tongues / Of all his flattering Prophets glibb'd with lyes / To his destruction, as I had in charge.

A person's mouth or tongue.

"Well, Sal, you mum your dubber pretty generally, but when you do slacken your glib you may as well do it civilly."