Why does anyone expect a specific answer to a non-specific question?
The more you can learn to help the client work through ambiguity, rather than expect the client to match your technical understanding and then be frustrated when they don't, the more successful you will be.
"The more you can learn to help the client work through ambiguity..."
This assistance implies expertise beyond just being a code monkey; higher-level thinking and problem-solving should definitely come at a higher price.
Granted, that goes with the territory of being in the service business. My gripe is that clients expect to pay for "just the coding" rather than the entire process of discovery, consultation, and strategy + coding.
The more you can learn to help the client work through ambiguity, rather than expect the client to match your technical understanding and then be frustrated when they don't, the more successful you will be.