There's a lot of sense in what you say.
I think there are people on here who cheat but not neccessarily the top ranked players.
Sometimes you come up against a player rated quite low who, all of a sudden , when in a losing position starts playing like a master.
They're the sad players who just can't bear losing under any circumstances.
They probably consult th ...[text shortened]... position up on a machine and follow the recommended moves
You'll struggle to prove anything though
I have to say that, for myself, I tend to play harder if I am losing but still think I am in the game. I've talked about it with my friends at the club, and we sort of decided that the top players know how to focus like that all the time, not just when they are losing. I have a reputation OTB for swindling lost games, even a piece down, and my friends give me grief for not playing that hard all the time. I get lazy, drop something, then start to concentrate. Here is an interesting recent OTB example (I was black):
I dropped a piece at move 6, got angry with myself for a split second, then told myself "Karpov would still win this game if he were playing my opponent, so the moves are there- I just have to find them." I just focused on development, exploited some dark squares, and in the end... still took 12 moves to finish a mate in 4 starting at move 22.
It was Game/60 minutes, and we were both a little short of time, but I still should have recognized that I could gain control of the c1 square. The Queen's ability to create threats by changing the color complex it operates on is a fine point I sometimes forget.
GM Lars Bo Hansen lives in my area, and he has often mentioned that he finds it interesting and humorous that American players start the game assuming the point, and tend to see a draw as a failure by giving away a half point.
He says he starts the game with nothing, and he views a draw as an earned half point. If his opponent errs, he gets the other half, too!