Proverb in the mouth of fools is like?

Proverbs 26:7-9
New King James Version (NKJV)

7 Like the legs of the lame that hang limp
Is a proverb in the mouth of fools.
8 Like one who binds a stone in a sling
Is he who gives honor to a fool.
9 Like a thorn that goes into the hand of a drunkard
Is a proverb in the mouth of fools.