Townsend,
I was mistaken regarding options... you may have noted my hesitation on in that regard. An option expiring would not result in a commission as the client did not fail to perform under the contract (as no performance is required from a holder of an option). My comment was primarily regarding failure to close a transaction (HUD or other). I was also clear that this was when you have an agreement with an agent. If you have such agreements in place, as promulgated in the State of Texas, a broker or agent has the right to their commission in certain situations (even without a transaction closing).
Having said that (and as I said in my earlier comment), I would think it odd for an agent to often pursue clients in this manner as the client is likely still on the hunt for a property and the agent likely prefers to keep the client happy and have potential on the next deal while avoiding the courts. As such, your ignorance of the contract you are signing likely hasn't changed your response to the
To further clarify, in Texas, agents use a standard TREC promulgated agreement to contract to represent buyers. It is called "RESIDENTIAL BUYER/TENANT REPRESENTATION AGREEMENT." Under Section 1 "BROKER'S FEES," paragraph C you will note the conditions under which your commission is "earned and payable."
Although based on your comments, I would encourage you to read the contract again, I was referencing the language "A person is not obligated to pay Broker a commission until such time as Broker’s commission is earned and payable." It continues to state that the commission is earned when ... (1) client enters into a contract to buy in the market area or (2) at client breach of broker's agreement. A contract is "payable" (1) at closing, (2) at client's breach of the contract to buy or (3) Client breach of broker's agreement.
As you can see from this language that legally, the commission becomes earned when a contract to buy is signed by both parties and become payable when the client does not perform under the contract to buy. So if you don't "close an excecuted HUD contract" you are legally obligated to pay your broker out of pocket presuming (as noted in my comment) that you signed the boilerplay buyer rep agreement.