If you're to hire an SEO then it becomes all the more critical that you hire a good one. It's important, lest you waste your financial resources. Recently, a cool list of 55 questions to ensure just that has become popular.
There are fifty question classified as Technical / Tactics; Analysis; Industry Involvement and some Open-Ended ones as well. The question are meant to test the knowledge and comprehension of a would be SEO on various topics such as their understanding of META tags, their opinions about link buying, or even if they understand the difference between SEO and SEM. Could he or she tell the why Wikipedia ranks so well for a range of search terms. One question is whether the would be SEO knows who Matt Cutts is?
The discussion about is has also caught up at Sphinn. One of the post rightly acknowledges need for technical as well as marketing knowledge for a good SEO.
Some people were even confused and some tried to clear it up.
All in all a nice set of questions, opinions, explanations and discussions. That's how knowledge becomes cumulative.