The best example I can think of, in my limited gaming experince is this
We were just starting our Dresden Game and we were all new to the system. Our GM was still getting used to Statting characters. One of our players was just freaking great at Social Conflict and discovered all these neat "tricks" you could do with it.
Our GM had made his Mooks and Villains tough physically, but had no mental or social armour/stresses.
So our "Talker" character was able to clear a room of Thugs by taunting them basically. While neat, it didnt fit thematically.
So during the next encounter, he basically said (Told us after the fact) I just gave them all an extra stress box for mental and made their defense a 3 (up from 0). Some would call this "Cheating"
So for example, this guy is saying I want to create a twist in my game where a character turns out to be a Mole.
So if you have a bunch of Wizards and stuff, running around this can be hard to keep things from them. So you cheat.
By cheat I mean. Cheat. Your PC wants to Roll Empathy of your Mole. You pay him a fate chip to not do it. Your PC wants to Rolls Empathy, but wait before he can Ninjas attack. Your PC wants to Roll Empathy, but finds nothing, turns out Part of the Moles Memory is missing due to fairy magic, or a Spell. Or Damn, your PC wants to Role empathy on your Mole, your Mole suddenly has a taggable aspect "Secret Secret are no fun..." and a Stunt that gives him +1 to deceit. Or you roll the dice and say "What did you get?" and then add 1 to whatever they said.
As long as the players dont KNOW you are doing it, who cares? The only time I've seen this go badly is when I had a GM want my character to get beat up in prison. My total was an 7 (+3 and a 4 is fists) he came up with an 8. I knew it was bullshit and he knew it was bullshit and I had my table ask me about it afterwards.
I mean are you guys stating out every little skill and power for NPCs? Even in the books they say something around the lines of Kincaid is +5 guns +4 Athletics, and everything else is a 3
I guess what I'm saying is what fun would it be if you show up 1st session an hour into gameplay you roll empathy, you beat by 1 and you find out the guy is a traitor you kill him THE END.