There's been a lot of discussion about what you consider "cheating" or "exploits", and what you don't do because it's not fair. However, what about the stuff that's NOT in any conceivable way "cheating", but you don't do it anyway, just because it doesn't feel "right" or "dwarvish enough"?
List your points of honor, and comment on other people's.
1. After the first caravan gets to my fortress, my exported wealth is NEVER allowed to be lower than my imported wealth. I'm not "losing a bunch of money by making poor trades", I'm "spreading the light of dwarven culture to inferior civilizations". I'm more than likely to just give 50,000 dwarfbucks' worth of stuff away to the caravans to keep my export/import ratio positive.
(edit) Also, Penguinofhonor brought up a point that I forgot to mention. I only trade items that my dwarves produced. I don't sell five hundred goblin-blood-spattered cave spider silk loincloths to the merchants. I throw them in the lava and decorate my stone idols with goblin bone and sell those instead.
2. Other than the axe and pick I embark with, my dwarves would never wield a weapon that wasn't forged in my fortress. As soon as I get a metal industry up and running, that axe and pick get melted down and replaced. Any metal item brought to my fort gets melted down and reforged, no exceptions. That dwarven caravan might bring me a dozen exceptional steel axes, but those axes get turned into steel bars and back into axes before my soldiers touch them. After the first year, no dwarf of mine ever has an (item) in his inventory.
3. I only kill nobles for one thing: killing useful dwarves for not meeting impossible demands. Incredibly difficult demands that can technically be satisfied, no matter how inconvenient they are, either get satisfied or I deal with the consequences. If somebody demands ten clear glass items on a map with no sand and no trees, but then they DON'T mutilate my legendary weaponsmith for not meeting a production order, they get to continue enjoying life.
4. Traps are to alert my military to ambushers, torture child snatchers, and make adventure mode tougher, not to replace my military. I only ever use a weapon trap if I get an artifact trap component (or maybe in my torture chamber), and I use a grand total of two (2) cage traps in my current fort. Not to make sieges easier, you understand, but because Armok is a bloodthirsty god and it is necessary to procure captives to sacrifice.