Are you sure they are cheating? Maybe they are just following the opening database to the letter and thereby playing like a GM until move 9 or so. Using databases, books of opening theory, etc., are not cheating in turn based play.
And a good scholar would also be reading up on middle game and end game theory for each situation he faces. I recently spent an hour or so reading a chapter on the bishop sacrifice before making one move. I convinced myself it was a "shoe in", and it did pan out as the book said it would. So that guy was not just playing me, he was playing me & John Nunn & Graham Burgess .
I've been trying to play turn-based games to better my slow play, and to take a decent amount of time to think about each position, but I think a lot of people might be cheating in turn-based play. I don't think all of the games I am losing are games in which people cheated, but I have played two people, in particular, who seem to consistently make devastating moves against me, and play very accurately. I examined one game afterward with my coach, a GM, and he said, "well, that was a waste of time. Ahhhhhh, I usually don't claim people are cheating, but given his USCF rating, this person played super strong." One of these players, plays very different quality games against me than against other opponents. This person has a blitz rating under 1400 on chess.com, a TT rating hundreds of point lower than mine, a USCF rating hundreds of points lower than mine, yet this person is working me (in particular) over like I am a complete bum.
This has me sitting here and thinking, wow, is there even a reason to play turn-based games on chess.com? I mean, the only people chess.com will say are cheating are people who consistently use computers (every move in a game or multiple games), so what is the point? I can beat Fritz set on 2000 and 2100, but I can't beat a USCF player rated under 1300 on chess.com's turn-based play. If I weren't so dedicated to imporving my game (and not wasting time!!!), I would retaliate. It's no wonder the ratings on here are so screwed up.
Is this basically the same experience that others are having?