is the King's Indian defense dubious

First of all, it was played by greats like Fischer. This means there is practical value to the opening that will allow you to score against players as good as 1970 world champions.

However it's true that it's not a good opening for modern top players. So as soon as you're a 2600 GM wanting to go pro (minimum 2700 FIDE) you'll have to start worrying about how the KID is not so good.

But until then it doesn't matter. (Nearly) any opening you learn well will score well for you, and that certainly includes the KID (but I recommend others because they're less work and offer black more practical play).

It's not dubious, it's just less preferred, but then so is the Sicilian these days. I don't know why he said it was dubious. The dragon might be considered dubious. 

Very strong players tend to agree on it being dubious. But for all us mortals that should not be of relevance. 

I have to wonder whether Kramnik is responsible for any feeling that the KID is dubious. He killed that opening as White: 52 wins, 44 draws, and 10 losses.

Maybe the entire Sicilian should be deemed dubious!

Maybe playing chess is dubious!

The KID is an extremely sharp opening, but the general consensus at the top level seems to be that it is not the best (or maybe not the most solid?) way to neutralize White's opening advantage (hence the lack of KIDs at the top levels). Personally, I think the tricky part about the KID is that White has so many setups that he/she can try along with all the mainline theory that Black has to know, and Black often needs to know against which setups he/she should play e5 and which setups to play c5, to which there are no real guidelines. You would need a good feel for the resulting positions to play the KID well; traditional engines are not going to help much as they are rather materialistic and may not see the danger for White until it is too late.

+1 

I never heard of the King's Indian Defense (KID) being called dubious (of course, I am no 2600 player yet xD), but I do think of it as an aggressive way for Black to play. Personally, I like seeing this defense if I am White: I find many of its games to be exciting to say the least. Do I think the KID is sound? I don't see why not. Do I think it is the "best" way for Black to play. I don't know, maybe some other openings give Black better chances? One thing for sure, I won't count this opening out - it is often times sharp and needs to be taken seriously: regardless of what a 2600+ player or chess engine claims at the highest levels; I play chess with players much lower than that and my games are not decided because of what opening is played

At our level ALL openings are dubious.

    However, according to the explorer of GMs games , after 1.d4, Cf6, 2.c4 it is played almost the same as 2.e6 that is the main move, 116.000 vs 159.000,and we are talking only of GMs. The rest of the options are far away

So at our level, chess is a draw because playing dubious chess is not a good idea.

Perfect game for amateurs: 1.Nf3 Nf6 2.Ng1 Ng8 3.Nf3 Nf6 4.Ng1 Ng8 1/2-1/2

Here you go.  An amateur can win with any junk in the world!  Enjoy!  Copy and paste the following - did it from a phone so it did not copy the hyperlink).

https://www.chess.com/live#g=4420499200

And yes, well aware I passed up mate in 1 and he should have promoted to Knight.  The garbage opening is the point, leading to a won position.  Did not care about the rest of the game.

Apparently Fischer, Kasparov, Tal, Bronstein, and Korchnoi all strongly preferred a dubious opening defense. It did not seem to hold them back much...........

i think the KID has suffered because the amount of resources like historical games and chess engines and theory on it has evolved to the point that a lot of its bite can be neutralized much easier than in the past. Something similar happened to the closed Sicilian with white despite Spassky's great performances with it.

Played yesterday at top level, https://www.chess.com/a/BeMV1pKgubAv, equal at move 12, and quite frequently played by Firouzja. He lost, but not by the opening

What is for sure is that it normally turns into very interesting games, although it is not easy to handle

But yes, I have heard the same comments, last time of Carlsen against Nakamura