"But I can assure you," she added, "that Lizzy does not lose much by not suiting his fancy; for he is a most disagreeable, horrid man, not at all worth pleasing. So high and so conceited that there was no enduring him! He walked here, and walked there, fancying himself so very great! Not handsome enough to dance with! I wish you had been there, my dear, to have given him one of your set downs. I quite detest the man."

I couldn't prevent the laugh after reading this, poor Mrs. Bennet , just imagine how she suffers from Mr. B's set downs.
It must be very painful ones to wish them for Darcy whom she detests. For sure Mr. B doesn't have any compassion on her poor nerves.