How to tell a good WP developer from a bad one?

Hi

I am now in the process of trying to find a wordpress developer. I know this is a very broad question to ask, but how would I (a person who can’t code) be able to deferentiate a good WP developer from an average one? That is, somebody who is more than simply a “template populator” and could actually code in logic in a clean manner.

Even asking this question I feel quite stupid. Nonetheless I’ll be really thankful for any helpful comments or pointers.