The big pain of repetitive ghost ships is getting 3 card hands over and over again; you need a treasure density of around a pure silver to get to province if you are just dead drawing with ghost ship. Gardens and dukes offer a shot to acquire healthy points from 3 card hands and provide a potentially superior alternative to ghost shipping.
While this may generally be the case for hand-size attacks, I think it is not really so with Ghost Ship (unless you have Workshop or Ironworks). The thing is, if you get militia'd, you can just chuck the green cards, but with Ghost Ship, they stay in your deck. So although you may be able to afford a Gardens with good 3-card hands (the kind you end up with against Militia), it's much harder to do off of 3-card hands where 1-2 of the cards are victory cards. And if we're talking about Workshop or Ironworks, it's not so much Gardens countering Ghost Ship as it just being a better strategy.
Also another point I guess is less clear than I thought and might be worth dwelling on: Like most discard attacks, ghost ship can be a trap in multi-player. If your opponents are battering each other senseless with ghost ships, you have zero incentive to keep buying ghost ships - they can keep each other down quite nicely and you can do far better with just about anything else. If Bob and Alice both play Ghost Ship every turn I can either get ghost ship and play 4 card hands just like them ... or I can do anything else with my 3 card hands ... like say go baron/silk road and have good cards.
This is a good point which I will mention.
This is what I think you are missing with monument. It isn't that monument is strong enough to counter, it is that +2 coins +1 VP is better for you than +2 cards. Because ghost ship doesn't stack, in 3 or 4 person games you can just grab some duchies, maybe the odd province, and and have a stack of VP chips large enough to beat a 6/6 province split. Your crappy 3 card hands are much better than their crappy 4 card hands as you can sift your terminals and can afford to do something other than a painfully slow BM deck.
Yeah, so I guess Monument is a good counter in 3+-player games. Maybe I should say something about that.
Another small bit that might be worth teasing out is that Apothecary can also function like a menage in that if you drop potions or coppers back into the deck you can be sure to draw them back out.
I didn't really want to go into detail about how all the cards listed as dealing with the top of your deck work. I think it's fairly obvious, and mentioning them is good enough.
For gardens and dukes, there are a lot of decks that can work with ghost ship to enable them. For instance baron. Estates without a baron are dead for dukes, barons without estates are bad until end game. Baron/copper/estate is a duchy (or duke), so you get ghost shipped with 3 coppers, a baron and an estate - get your duke. You get ghost shipped with 4 coppers and a baron - but the baron back get your silver (or whatever) and then try again to draw an estate in one of your 3 new cards. Likewise, say you are going develop/gardens. You draw develop and 4 coppers. then put develop and a copper back, buy a develop. You the get develop/copper/develop/estate/copper, then you can develop the develop into a garden & an estate and buy a copper. Or say you have remodel/bureaucrat going for dukes - you can kick back remodels, play the bureaucrat and then remodel a silver to a duchy. Yes BM/duke or BM/garden aren't going to work against ghost ship, but there are just a huge number of enablers out there for alterate VP that benefit from sifting.
BB:
More the situation would be something like this:
Your hand has apothecary/cellar/copper/monument/TR. What you could do would be to throw the copper on top first and then put on monument. Then play apothecary, draw the monument and the copper, cellar the copper to get the better of your two apothecary cards, and the TR the monument for 2 points. Depending on the copper density in your deck, this can be a net gain.
Just like with menage, apothecary won't make life better than not getting ghost shipped. But like menage, apothecary can mitigate the damage.
I don't know if it is worth mentioning, but it is something to think about if you are considering going ghost ship or some other attack (like rabble) and the other guy has apothecary.
