Additional note: My objection to playing much lower ranked players in cc isn't playing lower-ranked players per se. If you're good, and the rankings reflect the play, what do you have to be afraid of except the occasional slip-up (on your part) or brilliancy (on the part of a much weaker opponent)? I have always avoided playing opponents in cc with much lower ratings simply because you never know: (a) when your opponent is going to cheat; and (b) when your opponent's rating simply hasn't come anywhere near to catching up to his performance (assuming he's a new participant). If I am risking rating points, I prefer that, first, my opponent has some kind of track record so that I can see what I am dealing with; and second, if one is rated (say) 1500, why not play someone whose rating doesn't fall too far below that? Because what is the point of risking playing an 1100 player who plays like an 1800 because he decides to cheat in a particular game, when you could be playing an 1800 and risking a lot fewer points while obtaining the opportunity to gain lots of points if you should happen to win?
P.S. Perhaps I should also add that, in addition to the question of cheating *within the game* and in terms of one's opponent's level of play, there are a number of factors in my life which make it difficult for me to make a sustained "best" effort (or anything approaching this), so that I prefer not to risk a lot of points playing opponents in cc who are rated considerably (more than 100 points) below me.
All points well taken. My approach has been to play players rated 50 or 100 points below me so that I get a good game, but I also get to win, because to put in all those hours and days or weeks into an enterprise ony to lose in the end has been just too painful for me. But you guys have enlightened me to the value of playing stronger players nonetheless, so playing stronger players, maybe half the time, will be my new approach. Thanks for all the wisdom!