Can you add an S to an incorrect word if that word was not challenged?

The word QUAF* is played (it is incorrect as the correct spelling has two Fs). The word is not challenged. Later my opponent, who did not challenge the misspelling, adds an S to QUAF making it QUAFS.

I challenge and my opponent says that since the misspelled word was accepted then you can use it as a correct word and accept it with an S (since QUAFFS is a real word)...??

How to get 50 bonus points
in almost every game!

Hi - Fortunately your opponent is INCORRECT here. I say 'fortunately', because I can immediately think of a few horribly confusing situations that would result from such a rule.

Each and every word played during a game of Scrabble is independently challengeable. In your situation, you had every right to challenge QUAFS*, no matter what its history happened to be.

Thanks for an interesting question. I hope I've answered it.

All the best,

Scrabble Help from Word-Buff