volant: If he could have, he would have. Marking dead stones is a very hard thing for a computer to do and even the best go counting algorithms aren't perfect. In the two games listed, there aren't any dead stones (and in the second one, Gabby should have won, had she passed on move 34 and marked the 4 stones at B8 dead).

I think one or more referees would be a good thing for Go here, given the scoring issues that some games end up having, like the two Marfitalu listed.

volant: This problem could be solved, if playing a stone was mandatory after a decline of dead stones. A game could then go like this:

137 ...  pass
138 pass D
139 -    h7 (no pass!)
140 pass pass
141 D    -
142 h9   pass
143 pass ...

This, at least, avoids repetition of the same position for every dead stone marking phase and gives a chance for both players to mark stones dead.

The referees thing would be nice too ... I volunteer

hexkid: How would it be right if opponent makes wrong the dead stones and you would have to make a move? It might be that you would lose because of that.

Salkkuman: The player who (wrongly) marked dead stones is the one who has pass disabled, not the other way around.
Think of it as
player 1: I say these stones are dead
player 2: I don't agree, prove it.
player 1: ok, I play here (and lose 1 point)
player 2: Ah! you're right (but you're now losing by 0.5 points) ... pass
player 1: pass
player 2: mark dead stones correctly
player 1: decline
player 2: (Rats! she didn't fall for it) ... resign

hexkid: This is the way I see it:

player 1: I say these stones are dead
player 2: I'm not going to accept, so I can reduce your point count by one!
player 1: OK, I'll play here
player 2: pass
player 1: pass
player 2: Dead!
player 1: HAHA! I'm going to reject this, so you lose a point too!
...ad nauseum...

jurek: One of the games posted by Marfitalu could proceed to this position. Black has just (wrongly) marked all White stones dead and will have to play a stone on her next turn ...

Even if Black insist on playing on, at some point in time White advantage due to captured stones will be big enough to accept the wrongly marked dead stones :)

hexkid: What if, for example, there was a board position that was entirely filled, except for a seki position? The person rejecting the score count can force the other player to play, thereby forcing the first player to lose more points than by not playing.

hexkid: Proving stones to be dead can cost points!

Marfitalu: This problem could be solved very easily by following the rule used by the AGA: If both players pass twice in a row, the game ends immediately and all stones on the board are counted as alive.

This rule should be very easy to implement, and would completely avoid situations like this.

Marfitalu: In cases like this one, the player who claims a win (or draw) should report such a game to Fencer and he'll call it a win (or draw). That's how it works on BrainKing.

Marfitalu: If he's wrong, Fencer will tell it to him. :)