ughh what has the digital world done to classic games!? Now, because I only play the good old fashion scrabbles, I don't have to deal with this problem. I wouldn't say it's downright cheating, but more so I'd say it would be frowned upon to do that. But again, Buffyverse Fan said it well, those people rarely win, so I'm not too bothered by it.
Also, if the person would be playing against a computer, I guess it'd be a good way to practice and discover new words. Like when I practice playing chess I will undo and redo a bunch of moves to discover new strategies, but obviously I can't do that in a real match.