Just because you're listening to the client doesn't mean you're hearing the client.

Communication is key if you want to build strong relationships with your clients, and on top of this - an understanding of the work you are producing is key.

George Bernard Shaw once said that:

"England and America are two countries separated by a common language."

I think you could argue that in web design circles (and I'm sure other industries too):

"Developers and Clients are two separate entities that are also separated by a common language"

Imagine the scenario: You are building a new music website for a client, and they ask you to add a "shuffle playlist" feature to your product backlog.

Developers love to develop, but without using good communication in the process - via the PM or other (i.e. just letting the developers just crack on with the backlog items) the developers could easily upset the client by delivering their interpretation of shuffle (and not the client's).

Shuffle is a common term, used on almost every good music playlist device, yet it can vary hugely.

"Usually shuffle is completely random, but unfortunately it sometimes can repeat songs."

from: http://en.wikipedia.org/wiki/Shuffle_play

Just a few ways a developer could interpret  "shuffle":

1. Randomise playlist (I don't want to get into the truly random argument!) and play through the list until all songs are played once, then shuffle again (sometimes called shuffle repeat).
2. Play a song, then shuffle the list, then play a song, then shuffle the list...
3. Play a song, shuffle the list - refer to history and see if the next song has already been played, if so shuffle again, if not play it and so on..

Each of them would have different outcomes, and depending on the client - they may get infuriated that you have "mis-read the brief" (it happens!).

Going back to my original point; having communications with the client, and not just assuming the common understanding is sufficient can be the difference between a happy client and an angry client.