My mother was once wrangling with some guy at a desk in Florida.  She asked for my advice, which I gave her for free.

The next time we talked she said the guy said “your son must be the dumbest lawyer in New York!”.   It turns out she’d grasped the principle I’d explained, just had the action to take reversed.

“Ah,” she laughed when I told her.  I was only mildly indignant, the guy had a point if you considered only the benefit of the bargain I got for the law degree, licensing fees and dry cleaning bills.