A word in your hand

Did you ever have one of those games of Scrabble when really nothing goes wrong? Even when you’re praying that the next time you put your hand in the bag, it will come out full of ‘i’s or 'e's, out it pops with a’q’ – with, of course, a handy ‘u’ for company.
I had one of these a couple of nights ago. I got all the big scorers, both the 10s, both the 8s, the ‘k’(5) and most of the 4’s. And to ensure I didn’t have any problems putting them down, I got the two blanks and both ‘s’s. Doubles, triples, and double doubles – and, to make matters worse, a 7-letter word (50-point bonus.)
What could I do? A dyslexic chimpanzee could not have lost with tiles like these. My opponent could have been forgiven for accusing me of cheating. (She did not, but if Spears & Co. had made it out West it would have been shoot-out time. ‘Show me what you got in that other hand, Stranger.’)
By the end of the game we were barely talking, and the fact that, of our previous 130 games, she had won 73 and I only 57 had been forgotten. Only a long discussion on the mathematics of chance and a couple of glasses of lightly-chilled crisp white Burgundy averted a matrimonial crisis.
But the incident raises a serious ethical question. What do you do when you have an unbeatable hand? (Erich Berne – Games People Play – calls it the Gotcha syndrome.) Obviously you don't gloat, but do you keep playing to the best of your ability? Even if you are humbling the person you love? Or do you throw the fight?
The defence rests.