In the old Soviet/US rivalry days there was an accusation of cheating that I thought was novel. The accusation was that the Soviet players in the middle rounds were doing subtle not-right moves with the US #1. This forced the lead US player to put way too much effort into figuring out if it was some new line that he didn't know about and tiring him out. Then by the time he got to the final he was exhausted and confused.
No? It's a technique that could readily be done by one person, and teams are allowed to strategize. Bluffing/deception is kosher in chess, just harder as the key elements of the game are all public.
> During adjournments, players could count on the help of other strong masters, called seconds. These seconds would analyze the position and tell the player what they should play when the game resumed.
In parallel to this (and Bobby Fischer explicitly accused them of this), the Soviet players had already decided who would be the champion amongst themselves, and subtly let that player win his matches so that he was fresh and well-rested when he ended up playing non-Soviet players.
