What well known gambits are unsound?

Actually over-the-board, I have a plus score against players rated about 2300 with the Smith Morra but I still think it loses with best play on both sides!  Admit this is only a guess based on 20 years of experience playing that gambit! 

Halloween Gambit is interesting though maybe at points Black can decline or partially declined with a fair game.

Claiming Albin "unsound" is bullshit. The line given by you in this thread  (1.d4 d5 2.c4 e5 3.dxe5 d4 4.Nf3 Nc6 5.g3 Be6?! etc.) is self serving, because Black has another options like 5...Nge7 for example.

My particular line does not have to be good enough to refute the Albin Counter Gambit for the Albin Counter Gambit to be unsound. I do know that the team I played had studied this gambit for years and thought the move they played was superior to 5. g3  Nge7.

Of course, theory could have advanced since then.

If for example IM Pfren's suggestions tend to refute this gambit then this gambit may not be sound.  Part of my reasons for thinking this gambit is unsound is the way it is reached.  Moving the d Pawn twice with the black pieces strikes me as  something that cannot be "sound"

Regarding 5. ... Nge7 it "looks" fine for White to me but I have not kept up with current theory. 

I cannot "prove" the Albin unsound as someone can always come up with new moves against anything I might play or analyze. I am saying is I think with best play for both sides--that gambit is unsound.  If I ever meet God I will ask Him if the gambit is sound or unsound?

Based on my own experience playing Albin, I can only agree with pfren.

According to alexlaw logic, crappy lines advocated by him in this forum is total crap as they are almost never played, while Albin has been seen even in modern GM`s practice.

Which modern gms play the Albin?

It is my impression that the average opening advantage for White is about .2 of a Pawn?  [please correct me if I am wrong]

So, a theoretical win would be about .45 of a Pawn and this is just my guess.  I know that if I get an advantage like this [.45] I would expect to win...

Against the Albin I play

1.d4 d5 2.c4 e5 3.dxe5 d4 4.Nf3 Nc6 5.g3

and hope for the best. Black never seems to have anything that's all that convincing and he seems destined to struggle for a draw. Yet I would never pretend I thought that the Albin is unsound since that would indicate lines favouring white in all variations, leading to forced wins. I'm pretty sure they don't exist and that therefore the opening is "sound".

Ponz, I once played against the Albin in an off-the-cuff blitz game with John Littlewood, a member of one of my two clubs at the time. He played a very early  ...f6 as black and then got impatient when I tried to think for a minute (literally). This was unfair because he knew the variation and I didn't. Generally he was a nice bloke but I didn't like that bit of "gamesmanship".

Oh, he won and I swore to myself I'd never play the old so-and-so again.

Your post is worthless blah blah blah if you can`t show how White can get advantage after 5...Nge7.

pfren has mentioned GMs playing Albin.

Where did you get these numbers and how do you apply them to openings?

Pac was your question to me?  Re .20 a normal opening advantage for White is just my guess.  If I get close to a 1/2 pawn advantage I expect to win.

Somewhere there is an advantage enough that when you reach it or I should say when it is reached--if you play perfectly and your opponent does the same--you should win.

You misunderstood my question I guess. I mean when you have opening position - how do you known if advantage is 0.2 or 0.3 pawn?

You should start to use your brains if you want to become a good chess player.

You could understand that I asked him about patterns he use to evaluate advantage, if you used your brains. I `m bored of your ignorant remarks.

You made stupid answer to my question, which wasn`t adressed to you.

This Event Horizon ("the point of no return") in chess really exists, but it is believed to lie much further, somewhere around -1.4 pawn units. (Read: a pawn down in crappy position without counterplay.)

Nominally a pawn down in early middlegame when engine says -0.4, you should read as +0.6 compensation, which is huge. Engines still tend to overestimate material over other factors.

Edit: You must check engine variations for the reason. If the -0.4 evaluation comes from a line where the weaker side equalizes material and gets into crappy position instead and engine regards this as main line, then things aren't that good.

When I evaluate a position there are several factors to consider.

1. space advantage which I hope is self explanatory. It basically gives you more room to maneuvor. After this I will give an example of a space advantage for White in which many masters and grandmasters failed to understand this is a real advantage.

2. material advantage. Each piece is worth so many pawns. At the start of the game knights are probably worht 3 1/4 pawns and Bishops are worh closer to 3 1/3 pawns.  Each move you make can change the value of your pieces especially your bishops and knights. For example if you have most of your pawns on the black squares the value of your bishop which travels on the black squares goes down and the value of your other bishop goes up. In such a case you would probably like to trade your "bad" bishop for another bishop or a knight.

There are many end games where one side has a bad bishop and the otherside has a knight and the side with the bad bishops is practically or fully lost.

Combinations of pieces also matter. Suspose in the late stages of a game you have a queen and knight as your only two pieces [other than the king] and you opponent has Q and bishop.  The knight in this case compliments the Queen in that it can do things the Queen cannot do. The bishop in this case can only travel on one color square and the Queen can do this also.  So, often, A Queen and knight will beat a queen and bishop. Thus the Q and N is a material advantage.

Your moves in the opening. may cause a change in the value of your bishops.

If you  on the white side of the Maroczy bind with your pawns on e4 and c4 then your white squared B is hemmed in by your c pawn and you probably hope to get ride of it even before you make the set up with e4 and c4.

I have a friend who can explain better the changing value of the bishops and I will ask him to elaborate...

3. development.  How many pieces you have delveloped.  This is very important as it is my estimation if White is given 2 moves on the first move--he could play 1. e4  and 1. d4 and would very probably have a winning advantage--which means with best play on both sides he would win..

4. pawn structure.  This is a whole story in itself but in general the longer pawn structure you have the better.  so having pawn chains of 5 pawns and 2 pawns may be better than having pawn chains of 4 pawns and 3 pawns.

Of course there is much more in evaluating a position than this. For instance if you think your opponent made a positional error that is taken into account.

Sorry if this is rambling. ..

It seems better to show practical examples - lets say position after 1.d4 d5 2.c4 e5 3.dxe5 d4 4.Nf3 Nc6 5.g3 Nge7. How many "pawns" would you give for White -  0.2, 0.3, 0.4 or more?

For this please jump to the position after White's 16th move for an example of a space advantage

In the diagram White has a space advantage and the position has been evaluated as equal with almost no chances for anything but a draw by masters and grandmasters.

But in reality, White has the advantage in space and with good play can often turn this advantage into a win.  So White has some advantage and all Black can do in this position is to try and hold on and fight against the schemes of White.

In answer to the question by Pacifique in the position