Hum, I always thought Mountebank costs $5. I agree that 1VP doesn't make much difference very often. But having one Caravan Guard won't do much difference either. I assume you need some more to get a noticeable effect. In that case, you could also have bought some Great Halls, and I think 3-4 VP can make a difference.
Indeed, Mountebank costs $5. $5 is hard to hit in the early game, an extra +$1 that doesn't cost you a card in your hand is extremely helpful in hitting that $5, and if you fail to hit $5, sometimes there's nothing great at $4. Great Hall doesn't make that sort of a difference, it's something you buy over nothing very late in the game if you happen to get a dead turn. An opening Caravan Guard might actually help you skip Silver altogether if you need that, although it's probably not as good as Wishing Well or Oasis because it's a Duration so it misses the reshuffle more often. If it's easier to think of it this way, the difference between Great Hall and Caravan Guard is somewhat comparable to the difference between Copper and Estate.
Got your point. But often it fails horribly trying to remove the last junk cards from your deck, because you draw them before Lookout and have no way to discard them. So at least it's not as flexible as Forager or even Masquerade.
If you're drawing your deck anyway, there's no need to get rid of your last junk cards. If you're not drawing your deck, well, maybe you didn't manage to have a Lookout in your hand and a junk card in your deck at the same time this turn, but that'll probably happen next turn instead. It is definitely not even close to being as flexible as Forager, but it's not that much less flexible than Masquerade, which also forces you to leave junk cards in your deck so that you can pass them.
So you're relying on BM to get some decent payload? What if you don't get the payload you want? Then you've played some turns using a terminal Silver as your payload.
You will get the payload you want if your opponent ignores Black Market. And usually, there are many options there that can function surprisingly well as payload when you're the only one who has access to them. And it's fine if it's sometimes just a terminal Silver; a terminal Silver is bad, but for $3, a terminal Silver is pretty much the economy boost you expect at that price point so you're not really falling behind in terms of early game economy unless you have too many terminals, and the turns when you actually buy something great from the Black Market deck are totally worth it.
And since we're posting top 10 lists now, here's mint (excluding Adventures):
1.) Ambassador [X]
2.) Masquerade [X]
3.) Urchin [X]
4.) Swindler [X]
5.) Fishing Village [X]
6.) Steward [X]
7.) Forager [X]
8.) Menagerie [X]
9.) Watchtower [X]
10.) Hermit [X]