Bullsh_t or useful feedback? Do you listen to your customers?

Hi,
all of you run a small or middle business and maybe some of you run an Ecommerce site.
If a customer orders or wants to order something, do you measure his/hers customer satisfaction with your helpdesk? I mean: if the customer wants some further information about your product and he receives an e-mail from your helpdesk agent but the massage wasn't useful (or just dumb) so he/she buys nothing.
Are you trying to do something with it? How do you check the communication of your helpdesk agents?

Is there only nicereply.com or another tool to get some feedback from our would-be customers? Which one do you use?
Was the feedback useful? Did you fire somebody because you realized that he/she was bad in dealing with customers by e-mail and they ran away to another seller?

I was trying to find here a thread about customer relationships or customer satisfaction but it seems there is no such thing...