Aristotle said "All use metaphors in conversation, as well as right and proper words" (The Art of Rhetoric)
So, I suppose we are not using "right and proper words" when we do it.
They can make a point, but as you say, tend to be athought, or debate, stopper. The thing to do is ignore the seeming wisdom in an old "saw" as proverbs are sometimes called, and put your counter argument.
I like Andrew Bierce's updating of several well known sayings in his "Devil's Dictionary" :
"A penny saved is a penny to squander.
A man is known by the company that he organises.
A bird in the hand is worth what it will bring.
Better late than before anybody has invited you.
Half a loaf is better than a whole one if there is much else.
Of two evils choose to be the least.
Strike while your employer has a large contract.
Where there's a will there's a won't."
What the old cynic shows us in his inimitable way, is that those old sayings and metaphors should be challenged for the rubbbish they are.