What is said is often not what is meant.
Understanding a person’s desires can be more challenging than expected at times. People often choose the wrong words when expressing their ideas, and these can easily be misinterpreted further by those who receive the message. In everyday conversation, this may not be a big deal. But when one is gathering business requirements, errors in understanding can have significant costs.
Thus, one should always ask for clarification. Repeat the message back to the requestor in your own words. Use examples that illustrate the requirement in various scenarios, particularly around edge cases, failure conditions, and unexpected choices. Add pictures, diagrams, and mockups that further describe the system or feature requested. People often understand a problem a lot better when you draw pictures.
Discuss the requested enhancement and its context. Ask what happens before and after, so you can better understand the necessary states of the application.
And most importantly, don’t take simple requests at face value.