That is a really great questions. Unfortunately I think the best answer is that you just know.
Personally, I think you should feel confident and comfortable that the agent is going to actually be representing your best interests and has an executable strategy for getting you the best possible terms for your property that can be clearly articulated. I would also look for an agent that is willing to tell you things that you might not want to hear. I find that all to often, agents will say whatever they think you want to hear to get the listing.
I am happy to talk to you to find out if we might be a good fit. I have an excellent track record with people in your position. Take a look at what some of my past clients have said about me by following the link below.
Best of luck!