"She's too sweet to be wholesome.

Fair words butter no parsnips.

Look out for a tongue that's smooth on both sides.

What does the Bible say of the hypocrite?
'The words of his mouth were smoother than butter.' I'd rather have honest vinegar!" I stood too much in dread of her frankness to ask if sugar is never honest, or to speculate audibly why she chose parsnips with their length of fibre and peculiar cloying sweet, as types of daily living.
The adage seemed droll enough to me then, and it is odd even now that I have become familiar with it in the talk of old-fashioned people.
Interpreting it as they do, I dispute it stoutly.

Parsnips may be only passable to most palates even when buttered.