Final answer:
In real estate, the most common client complaints often stem from the failure of the agent to disclose material facts about a property, which is a legal requirement and crucial for a client's decision-making process.
Step-by-step explanation:
The most frequent basis for complaints by a client in the real estate business typically includes issues such as the failure of the agent to disclose material facts about a property. While agents are not in the position to provide legal advice or financial advice, and extending the closing date might be an inconvenience, failing to disclose significant information that affects the value or desirability of a property is a serious breach of an agent's duties. Disclosure of material facts is a legal requirement in many jurisdictions, and failure to do so can lead to lawsuits and financial loss to clients, making it a common ground for complaints.