Opening books' inaccuracies

 I don't see the connection with 1...a5.

neither do I, other than the queen

  Yes, but you quoted the post addressing the proposal of responding to 1e4 with 1...a5. So the connection with the idea of 1...a5 seems non-existent.In other words, your post could stand on its own.

  That's one. Two, what is the point conveyed by that line of Caro?

 A military project concerned with 1...a5! 

 All kinds of mediocre people here.

Can't remember an inaccuracy from a dedicated opening book, but one intermediate-level book with a large opening section classified the following Nimzo-Indian line

as dubious, because "the pawn has no business on a3 and in Nimzo-Indian black usually ends up taking on c3 anyway", or something like that. Apparently this simply isn't true, and it was probably just a personal bias of the author who had something against this particular line.

John Nunn said it correctly, don't trust analysis in opening book, there could be some errors.

 If I remember correctly, Batsford Chess Openings suggested this line in the 1980s.

 It depends who’s doing the analysis. Some authors are intentionally misleading, like Sveshnikov in ECO’s B22, in a traditional line, where he conveniently stops right after 15...f6! giving the impression that Black has an advantage, but he left out that instead of the source-game, which Black did indeed win after 16. f6?!, White could have played 16. e6! and obtained an advantage, according to his own discovery.

 No doubt, he wanted to make a Black player play ‘by the book’ and then apply the surprise, which is turning the tables, especially since B22 was ‘putting food on the table’ for his entire family, as he said, for decades now.

Thanks IM Poucin, the limit mobility of the Bishop to a safe square. Sometime its the simple tactic that we are blind to.

That is so dishonest, we the consumer rely on them being diligent or honest effort, not withholding information that can be critical in a position. Korchnoi did the same in his King's Gambit book and that is why I never bought a book from him again, Psakhis, he withhold critical information in the advance variation of the French defense, after that I never bought a book from him.

There are writers who warns us against trusting anyone when it comes to openings. I myself relied on Psakhis in the French Defense, especially Winawer, but didn’t find any suspicious lines, perhaps because I always have 10 other sources dealing with the same lines, for cross-reference. Fortunately, I only borrowed Psakhis and used it temporarily as an extra reference book.

 Here I will present a much smaller error, but quite inexplicable. In MCO 14, Grand Prix Attack, a main line is the line that I play as well: 1. e4 c5 2. f4 d5 3. exd5 Nf6, where the main line ( there and in NCO) goes, of course, 4. Bb5+ Bd7 5. Bxd7+ ( the odd-looking 5. Bc4 doesn’t intend to hold on to the extra pawn for as long as possible, as in the main line, for after 5...Bg4 6. Nf3 Nxd5 And the pawn is lost, and equality is achieved after 7. Nc3 e6 8. Bb5+ Nd7 9. h3 Bxf3 10. Qxf3 a6 ). So 5...Qxd7 6. c4 e6 7. Qe2 Bd6 8. d3 ( rather than 8. dxe6, to discourage  ...Nc6 and castling long, although that remains a possibility) 8...O-O 9. dxe6 ( now Pd5 was threatened, that Pe6 was no longer pinned) 9...fxe6 10. Nf3 Nc6 11. O-O ( 11. Nc3 e5!) 11...Rae8 12. Nc3 e5 13. f5 (finally returning the pawn so that the diagonal for Bc1 is open, in order to get to g5) 13...Qxf5 14. Bg5 e4 15. dxe4 Nxe4 and NCO stops here, giving no game and equality. The game, of course, is Short-Kasparov, Paris, 1990, and MCO 14 notes the source-game and then continues, 16. Rae1 Nf6, giving the impression that these two moves were not part of the game, but its own improvement discovery, although also with equality.

 First of all, the situation on the board is not even a quiet one, so if you don’t stop at move 15 like NCO you have to continue a bit more. The white queen is attacked, after all.

 Secondly, of course it is part of the game, and I don’t mind the pawn structure for Black at all, after 17. Qd1 Rxe1 18. Rxe1 Nd4 19. Bxf6 Nxf3+ 20. Qxf3 Qxf3 21. gxf3 Rxf6.

  One more error in the opening books.

I have William Winters 'Chess for Match Players' which is a very good book in many respects. He recommends opening repertoires for 'combinational' as well as 'positional players'. There are some good chapters on middle-game and endgame. Some of the opening advice is almost laughable now. He says he can't recommend the Nimzoindian defence because the Samisch variation is so strong !

Or an innocent mistake of inserting the parenthesis with the source-game info before the last move, a practice ECO uses, to separate suggestions from actual moves.

 Still an error.

 In response to 57.

 I don’t know about others, but I prefer to use opening books as the skeleton of my opening repertoire, choose what appeals to me as a player and then develop from there with more lines and moves.