Spy is actually a pretty decent... well, not counter, more of an ameloriation of Ghost Ship. If your opponent plays Ghost Ship and you have Spy in hand, then put a crap card from your hand on top of your deck first, then a card you want in your deck. That way Spy will draw the good card and discard the bad card, ensuring your next hand is not polluted. Of course, if your hand has three cards better than Spy, just put it on top of the deck, unless none of them are cantrips.