The Meaning of Life, the Universe, and Everything.
While they certainly take advantage of mob spawning and behavior, I wouldn't call it cheating. I enjoy just building traps around mob spawners (especially spawners - [>>-i>] factory!) because that takes a lot less time and effort. Besides, how much do you *really* need?
invedit isn't cheating.
"Cheating refers to the overt or covert breaking of rules to gain advantage in a competitive situation. The rules infringed may be explicit, or they may be from an unwritten code of conduct based on morality, ethics or custom, making the identification of cheating a subjective process. " -Wiki
minecraft ssp isn't competitive, therefor you cannot cheat in minecraft ssp. Plain and simple.
I see these threads every few days. In every one of them, the general consensus was that NOBODY COULD AGREE. Half of the players say they don't like them because they can sit without doing work. The other half say it's balanced by the work done to make it. And those few others will write comments like me or say: It's a sandbox game, there is no cheating, or: Notch put this stuff in game. He gave us the means to do these things. Therefore it is allowed. NOBODY REALLY CARES!!! except the purists