The problem with the cheating is that it requires her to be (1) smart enough to not get caught cheating in a high stakes poker game and (2) dumb enough to cheat in a ridiculously obvious way. Those seem mutually contradictory. If you can pull off the cheat you'd be smart enough to cheat in a less obvious way.
I suppose Hanlon's razor is adequate here - "never attribute to malice that which is adequately explained by stupidity".