Miles has always gifted viewers with well-thought-out devil's advocacy in the midst of frustradedly self-indulgent, narrow-minded and over-bearing lead character characterness.
For example:
Jack: We have to blow up the island and kill a bunch of people because i'm in love with Kate and i blew it.
Sawyer: You're out of your damn mind! And you make me angryyyy!
Juliet: No! He's right! We have to detonate a nuclear weapon because otherwise you'd be with me and never leave my side.
Miles: Umm... soooooo, have you guys, like, thought about what you're about to do? And that maybe it will cause the thing you're trying to prevent in the first place?
In "Everbody Loves Hugo," he (an authority on communicating with the dead) approached Hurley and asked him skeptically about his dealings with the dead. We could tell by his expression that Hurley's report doesn't fit into his vast and well-paid experiences with dead people.
Furthermore, Walt (not dead), Richard's wife, Christian Shephard, and others have appeared as apparitions instructing people to do things. I guess they could be stuck on the island and unable to move past it because of their links to their loved ones, but many of them have never been to the island. And alot of the time, their presence is a very sinister one (Mr. Eko's brother) and they lead our beloved characters into snares of doom (Shannon chasing Walt and thereby getting shot by Ana Lucia).
So this is where I go out on a limb: Season One, Episode 5, Jack goes chasing his dead father into the jungle and tumbles down a hill and rolls off a cliff. Locke miraculously appears and pulls him up. Similar thing happens in season 6 when Flocke brings Sawyer to the Number's Cave and Sawyer nearly plummets to his death, but Flocke pulls him up, saving his life. Not a huge coincidence, I know. But I don't think it was Locke pulling Jack up. I think it was Flocke, which would fit since Jack was chasing his 'father.' I think the sinister dead apparitions and the whispers have been Smokey all along, and that Smokey changed from dead Christian Shephard into Locke to pull Jack up. How would Locke know where Jack was to save him? It was quite a fast and random downhill tumble.
Smokey appeared to Hugo as Michael, knowing that Hugo believes that he communicates with authentic dead people and that if he appeared to him as Michael, he could convince him to come meet up with Locke and bring Jack and Sun with him to his camp so that he'd be one huuuuge step closer (Jack is a stubborn dude. And Sun is too, after seeing her sprint away from Flocke after he promised to reunite her with Jin) to having all the candidates under one roof.
Maybe it was a dead Michael telling Hugo whatsup, but I strongly disbelieve that the whispers have always echoed purgatory. I also get the feeling the writers don't really want us to believe what Michael told us, which is why they gave Miles his routine level-headed line this episode.
But then again, I also don't believe the whole 'candidate' smoke screen. So maybe I'm the one in need of devil's advocacy. Hook me up!