Blindfold tactics

There is an assumption from players not that familiar with blindfold chess that it is very easy to lose track of the position. I even read a story once about how a group of players attempted to so the seeds of confusion in a blindfold simul by starting with different first moves but transposing into the same position after 4 or 5 moves. The simul player dealt with this by taking a bathroom break, and climbing out the window into the night.
Nothing so drastic for Magnus Carlsen, although his first move against Vassily Ivanchuk (1.a3!) looked like an attempt to baffle his opponent. However Ivanchuk was not confused and instead demonstrated an even more important blindfold tactic on move 31. "Play the best move in the position"

Carlsen,M (2813) - Ivanchuk,V (2748) [A00]
19th Amber Blindfold Nice FRA (1), 13.03.2010

1.a3 Nf6 2.c4 c6 3.Nf3 d5 4.e3 Bg4 5.h3 Bh5 6.cxd5 cxd5 7.Nc3 Nc6 8.Bb5 Rc8 9.g4 Bg6 10.Qa4 Nd7 11.b4 e6 12.Bb2 Be7 13.Bxc6 bxc6 14.Qxa7 c5 15.Qa6 0-0 16.Qe2 c4 17.e4 d4 18.Nb5 e5 19.h4 Qb6 20.a4 Qb7 21.Ng5 h6 22.h5 hxg5 23.hxg6 fxg6 24.f3 Bxb4 25.Ba3 Bxa3 26.Rxa3 Qb6 27.Qh2 Qc5 28.Qh7+ Kf7 29.Ra1 Nf6 30.Qh2 Ra8 31.d3 (D)
31. ... Qxb5 0-1