Some out of the box ideas...
Start talking to agents. When you see signs on homes for sale that are similar to yours, call that agent and ask a few questions about the home--how long on market, how big is it, have there been any offers. The way they talk to you will tell you a lot about how they represent the Seller. Do this for several agents. Visit open Houses. Talk to the agents there--same sort of questions.
When you have spoken to a few, go to more open houses or phone more agents, and ask them about the other agents you have spoken to! The agent you are asking the question of will reveal more about himself or herself, than they will about the agent you ask about! For instance, if the agent you are asking, says "oh agent X? Stay away from her--she's awful" then you will know that the speaker doesn't work well with other agents--which can mess up the sale of your home. Or, if the speaker says, "I've never worked with agent X, but she has a good reputation," then you have an agent who is at least diplomatic or discreet.
That is a way to do some research sort of "under cover" so you can pick out your top candidates.
Put a For Sale by Owner sign in your yard. You will end up with the most aggressive agents calling you and you can interview them at your leisure!
There are SO MANY agents, and there are lots of good and great ones. You should be able to find some good candidates without too much trouble. They will know that there is competition, so they will be on their toes! Be sure that they have shown you the Blue Pamphlet, and told you about The Law of Agency in Wa State. That will weed out the careless ones. Ask if they are full time agents. That will weed out the ones with priorities that don't match yours. An agent can moonlight and still be a great agent--just listen carefully to the answer to see where their priorites are.
Make sure that you can communicate well with your agent. Without good communication, you won't know if they are doing a good job or not!
Best of luck!