No, the cards cannot be examined. But with audience management, it shouldn't be a problem. Either way, buy the trick; it's one of the greatest packet tricks ever invented. However, if you want a trick which is examinable, check out Megawave by John Bannon. Not exactly similar to Twisted Sisters but very close.
Which ever one you go for, you are going to learn an amazing packet trick which will astound your audiences.
Hope this helps with your purchasing decisions.