This is the number one reason I love static analysis tools like ReSharper for coding. I write a piece of dodgy code, and it tells me "Hey, this could result in trying to access a null pointer", or, "Hey, dummy, this conditional is logically inconsistent and the block below can never get executed" or "Hey, you can rewrite this great big loop with a simpler LINQ statement." Then after a few times of doing this, I internalize the rules, and start doing it on my own.