Mandy Thompson is quite a complex investigator to take, not only her deckbuilding options but also her weakness seems to have more to it than meets the eye. I am not completely sure, if I am doing it right, but as far as I do understand the rules as written ("When a player is instructed to search for a card, that player is permitted to look at all of the cards in the searched area without revealing those cards to the other players.") the target of the search for certain cards is the entire deck. This is true for the upgrade No Stone Unturned for example. So if you use such a card, than you will always find Shocking Discovery and by that set it of in a "controlled environment" so to say and don't have to worry about it any longer.
Having said that, as long as you do not have found Shocking Discovery yet, than a card searching the entire deck is pretty valuable for Mandy to have. So not only the expensive upgraded No Stone Unturned which you might probably not want to waste on this, but also cards like the 0xp Research Librarian all of a sudden look completely different to me. Even some encounter cards might help, like SPOILER or SPOILER from Path to Carcosa. The latter will also surprisingly be completely canceled as far as I do understand it.