Idea of cheating is rather difficult to classify with single-player game. Particularly a very modifible one, it could be anywhere from the 110% coin smelting result in default to reactions to turn every dwarves into bronze colossus and to make a million bluemetal wafers. Or just giving dwarves bone of steel or making multiple civilization to get bigger sieges.
Then there're the split between legit exploits and outright cheats that people debates with splitting bolts smelting and cave-in traps. And quantum stockpiling. And so on...
I don't uses any mods except personal ones, like making all underground plant plantable year-around and expanding bone and stone equipments. No utilities either.
Something valuable for nothing or modifying embarking race to be next to invincible against incoming sieges would be something close to cheating in my book, if not for testing use. Stuff like bolt splitting and over 100% smelting return's more in providence of exploits since it takes effort to do.
Do note that being able to import steel bar from dwarves when there're no iron from their civ could be considered a cheat by above standard, and overly abundant egg meal also