The spirit of the game...

[Der Kuenstler]

I read that there was a Polish guy who discoverd to "view" or "read" the PBEM files before he'd sent them back. He kept on making new files in a certain situation until his gun did kill that enemy tank with the first shot instead of a miss or just hit without any consequence.
I would think this behaviour is a bit contrary to "the spirit of the game".:P

I'd say that goes over the line - it is not something normal game use would allow you to do - I would call a guy out as a cheater on that one.

Changing the unit stats in the editor of an established scenario before sending it out - I'd call that cheating.

Using a map over and over when you've told your opponent you've never used it - cheating.

Setting parameters to benefit your side in a quick battle - not very nice but it's not cheating. You have the right to make any offer by Blitz rules and it is then your opponents right to refuse the offer.

A wise person once told me beware of anything you do that you have to look both ways first before doing it, to make sure no one is looking. Probably a good rule to go by here.