I don't believe she gave definitive dates.
Why not?
If she would, everyone could check out her story.
Did she buy a plane ticket or make a reservation herself? She could prove she was in town during the right time. Does she have any documents of this sort?
Herman Cain was a notable figure already, where he was at a particular time might be findable , if he was elesewhere this story falls apart, if he was in town did he rent a car, upgrade her room, etc. etc.
Just finding Herman Cains credit card being used to buy gas some miles away could be enough.
The truth might really be out there this time.