On Hiring Drupal Developers

Every technology that becomes widely popular as quickly as Drupal has will certainly attract individuals looking for a quick buck, without concern for real skills and experience.

Drupal's incredible flexibility means that most problems can be solved in more than one way; but some of those ways are not "The Drupal Way" and can result in more time and expense down the road, when you want to change or expand your site. We are frequently contacted by organizations who had hired a previous developer who couldn't deliver what was needed, or who delivered a mess of code that had to be untangled before new work could begin.

This article will help you avoid hiring someone who can't walk the talk:
Five Questions you should ask your Drupal Developer

We'd like to add just one more question to this list which should give you a sense of just how knowledgeable your potential developer is in The Drupal Way:

6.) How do you decide when it's better to implement an existing module, and when it's better to write custom code for a particular task?

Lastly, we'd like to encourage you to trust your BS-detector. If the developer says something that sounds inconsistent or unlikely, point it out, and ask them to explain. If they aren't ready with a clear answer or an example project to substantiate their claim, you may want to consider looking elsewhere.