There seems to be a misunderstanding from many here about "present all offers". A listing agent must present all offers received to a seller (your state may be different), but this does not require a selling agent to represent a buyer unless there is a Buyer/Broker Agreement stating otherwise.
Just as a client can fire their agent, an agent can also fire their client. I have fired many clients when they ask me to do illegal, or unethical things. Sometimes I have seminar investors who want me to write hundreds of ultra low-ball offers. They are generally a waste of a lot of my time, effort, and reputation, but the investor has nothing to lose because they don't have any skin in the game and only an LLC name on the contract. I tell them I'm not the agent for them. Usually, investors need to find a gullible and inexperienced agent fresh out of school to do this.
I have also fired clients because we just have personalities that just don't get along, and some that were downright crazy. At one time I had several crazy clients making my life miserable. My broker called me into his office one day and said: "The key to a happiness is to remove the crazy from your life, they are not worth the trouble". I took his advice and he was right.
If your investing style is in conflict with your agent, I would suggest that you find a new agent who will work with you. Just be upfront with agents about your acquisition strategy so you don't waste your or the agents time. One word of advice, I'm not opposed to lowball offers in the right circumstances and I'm getting ready to write one now, but be careful because sellers are emotional and if you insult them they may refuse to even look at any followup offers. Good luck.