I never cheat intentionally when given clear guidelines about character creation, specific house rules, etc. I suppose I begin to cheat, or what others may call it, when the DM is very undecided about rules, books, and features and is reluctant to delve into a character's daily use.
If I have a responsible and dedicated DM, then I don't cheat. If I have a wishy-washy DM, then I'll probably cheat unintentionally because I haven't a clue to what is going on or have the care to manage such chaos.