When customers come to you with a problem, they are vulnerable and, in their own way, broken… You need to fix the customer as well as the problem itself. Fixing the customer means empathizing with him and recognizing the inconvenience he’s gone through.
The users’ purpose is to transact, so let them. No marketing information is worth asking for it it prevents your users from becoming customers. What good is additional marketing information if it means losing customers? Every piece of information asked for must have meaningful purpose to support the current task.
On the web, you don’t sell to people; you help them buy.
We shouldn’t be defining our users strictly according to their age, occupation, and shoe size. Instead, we should define users by whether they are at the site to browse or they know what they want and want to transact right away. By designing you site to enable your users to find what they need at their particular decision stage, you can be more effective in meeting their needs and converting them into customers.