First off, I should point out that in online chess, using references like opening books and databases is NOT cheating, never has been here.
That said, the discussion of cheating is not really supposed to take place here in the public forums of the site. There is a "Cheating Discussion" group that houses all the cheating related talk.
I am browsing a lot profiles and seen some users disabled for some reason.
How do you prove thats its really you playing and not chaeting? It's really hard to prove, and its easy to cheat (consults to a chess computer or references) because you have 3 days to move.How do you know when your opponent is not playing fair? Here are some tips you can check:
1. Your opponent takes a long time to move every single time, even if your opponent is online, and simply when your opponent's best move is obvious and still taking a long time.
2.Your opponent never play Blitz, Live chess or 960s. These games requires quick response, and unusual techniques for the 960s as conventional chess openings are usually practically useless, thus references will be useless. If they do play these games, check out their ratings and some of their games.
(It doesn't mean that you have to play Blitz if don't fell like it..many classical players like me is not a huge fan of blitz before..but I started to like it over the years.)
3. You know that a strong player usually stick with his/her favorite opening when playing white pieces. Check out your opponents previous games when playing white pieces, and see how consistent his openings and mid-game and how he put efforts in controlling the center..you know what I mean.
4. When you opponent is playing black and started responding textbook moves(and responding 3 days every time), try to deviate a little bit in the usual opening variation and see if the response is still textbook :)
5. I played a lot of players in Facebook chess who uses computers and references ( solid openings, sometimes makes brilliant sacrifices) to cheat and trust me, they always make the following mistakes(usually in the mid-game):
1. Abandoning the center just to get worthless material advantage.
2. Failing to position and prepare for the end game.
3. Errors are usually strategic, not blunder
4. Weak in mid-game and end game
Well its really hard to prove..thats why I have this proposal to all players who played with me before. To prove that its really you and its really me..lets play blitz..doesn't matter how short or long....challenge me when i'm online and let have fun! :)