It’s difficult to hear this, but your “pain-in-the-rear” prospect has every right to be a “pain-in-the-rear”.
One of the hardest thing to do is to swallow pride and keep our ego in check when we deal with difficult/arrogant/know it all prospects. However, who are we to judge?
Do yourself a favor and keep your ego out of it.
Focus simply on helping them solve their problem and pick up a check for it. (Their money spends just as well as the nice prospects)