So from reading the responses to this question that have already been posted, you surely have a good idea as to why one would want to use a buyers agent. I just wanted to reiterate one point that was mentioned before: EVEN IF YOU DO NOT USE A BUYERS AGENT, YOU ARE STILL PAYING FOR ONE! What I mean by this is whether you use an agent or not, the commission paid to the selling agent is likely to remain the same. This means that you are PAYING FOR AN AGENT WITHOUT GETTING THE PROTECTION OF AN AGENT.
Again, I understand that you have had a bad experience. I would recommend being very deliberate in working with any professional, but especially in working with a Realtor on a home purchase. This is likely to be the largest transaction that you have ever undertaken, and having the right information, and a professional to guide you through the process not only saves you time, but potentially a significant amount of money.
I would suggest that you look for an agent who is willing to sit and listen first to your needs. If you have already identified the home or the market area where you want to buy, your price range, and your preferences, then share these with the agent. Communication is the key here. There are many of us agents here in the St. Louis Area who genuinely value our client's time and will do anything possible to help you achieve your goals. Take some time and look for an agent who can make your vision their own.