Mikenas Defense:Good or bad?

This defense is characterized by 1.d4 Nc6.In essence,it looks like d4's counterpart to Alekhine's defense.I've played this a few times,and the results were mixed.Is it sound?Any lines in this relatively uncharted territory that kill black instantly?

From what I know, it's playable, but it leaves Black with an inferior game when compared to the Alekhine.  There really isn't any real refutation to it, but a major difference is that it develops the queen's knight instead of the king's knight, so castling will take a while for Black.  I've never played it myself, but I had someone play it for a bit before switching to the Black Knight's Tango, which is 1.d4 Nf6 2.c4 Nc6!?.  I personally don't like the looks of either, but from what I've heard the Tango is a perfectly playable weapon, so maybe that will interest you.

I predict any old random move in the centre is good.

That is the Nimzowitsch Opening. It's not "relatively uncharted territory" at all, people have been investigating it in-depth for decades, it has whole chapters written about it. If you're looking for uncharted territory I suggest looking further than move 1. 

Like Owen's, the Grob or the Latvian gambit it's considered "unsound but not a complete joke". 

No,it isn't.Nimzovich is 1 e4, Nc6.

That's not the Nimzowitsch at all, which is 1.e4 Nc6, which although has been researched more recently still has a decent amount of unexplored territory, despite several BOOKS (not chapters) about it.  Besides, neither the Nimzowitsch nor the Mikenas are unsound, although I would rather have the Nimzowitsch any day.  Besides, of your three examples, I would consider only the Owen's Defense fitting that description.  The other two, however, ARE a complete joke, especially the Grob.  The only thing I agree with would be looking past move 1 for uncharted territory.

It's perfectly OK, Short has played it many times.

I don't know anything about this opening but I would guess that white's three thematic replies are 2 c4, 2 Nf3, 2,e4.Personally,I'd go with c4,expecting a transposition to Chigorin defense. 

...to meet 2...e5, which is a more common move, and the one Short, Stevic and a few more 2600+ players are employing.

There are 469 games starting d4 nc6 listed on chessgames.com

Thx pfren!do you think you could show us a typical sequence with ..2 e5?

What pfren is talking about is a few abherrent players out of hundreds or thousands of players who often play those moves in:

1) Blitz.

2) In simul. 

3) To avoid their opponents specifically preparing against their openings. 

4) To increase their publicity. Every time the word "Short" is mentioned anywhere, that slightly increases Short's notoriety and value.   

Short does not believe 1. Nc6 is actually "good", only that it's playable and not immediately losing.   

I just checked it in fritz,it seems there are basically two thematic moves after ..2 e5, 3 d5.So,1 d4, Nc6 2 c4, e5, 3 d5, Nce7 4 Nc3.Or,1 d4, Nc6 2c4, e5      3 d5,  Bb4+  4 Nd2.

You seem obsessed with commenting on every one of pfren's posts, like some kind of weird fangirl.  Just pointing that out.

Back to chess,the way I see it is that Nc6 as a response to d4 is a chameleon opening,having both independent value of its own,as well as offering a wide range of transpositional possibilities.All in all,fully playable and rather better than it looks.Just my opinion..

so what does black play against 2 Nf3? d5 to transpose into a Chigorin?

2...d5 is the most rational reply- Black has avoided some of the most dangerous white replies to the Chigorin. But 2...Nf6 and 2...d6 are quite playable. Of course you must be aware of some subtleties- e.g. never fall into this one:

...and Black is in grave trouble.

hmm...I've played that same trap before in a similar position.I think it also arises from the Marshall Defense (1.d4 d5 2.c4 Nf6).Interesting.

How about 2 e4 guys?Well that would transpose to a Nimzovich defense,wouldn't it?

yup.The Nimzo defense is solid.