I dont use cheats at all on my main file,and I have completed the game 100% with a criminal rating of "assasin" I have a spare save where I use edison carters cheat device. (it can spawn cars, create your own objects in the game, infinite health, armour, floating cars,and moter bikes rocket speed etc)
using even one cheat will result in you losing a LOT of criminal rating points, even though rockstar was too lazy to put the number counter in there.
There is no good, there is no evil, there is only power, and that power will be mine.