This has been an interesting discussion. I don't know if there is a really reliable way to test computer use. I was a 2300+ correspondence play and a Master OTB and in the ICCF where you could use computer engines legally for chess you found when using the engine often there were two or three fairly good choices and often what choice you chose was the style of play you liked. Engines also can return different results depening on how powerful the CPU and even if you had a lot of games to examine you almost would need to examine them on the type of Computer that you thought the "cheat" might be using.