I think Aaron summed it up perfectly!
I would like to know why Joe would advise you against signing a contract with an agent. I'm not sure how it works in your state, but in the State of Wisconsin, if you do not have a signed contract with YOUR agent, then that agent automatically represents the seller. Furthermore, if you want an agent that is going to take you seriously and commit to you, they will expect no less from you. If you are a serious buyer, you will want to interview several agents and ask friends, neighbors, family, co-workers about their experience and find a good fit for you. Once you've done that, pick one agent to work with and you will have the best results!