Should client service delivery people be responsible for upsell and resell or is that bad for client trust?

In my experience, it is bad for customer trust. In addition it skews performance metrics away from creating a positive customer experience, forcing customer service representatives to focus on sales goals. The result of this is that customer service representatives are less focused on addressing customer concerns and more focused on redirecting the conversation to sales pitches. Notably, this not only undermines customer service but, ironically, undermines sales, marketing and product design as well. The best sales strategy is to find ways to meet customer needs by matching those needs to existing products and services, and by adapting products and services offered to meet the demands of customers. Traditional customer service does this very well, as a service focused representative will notice trends in customer demands that are not being met and, provided an open business atmosphere, pass these unmet demands on to their superiors. In an environment where specific sales goals must be met, however, this attitude can be misread as excuse-making and attempts to match services to customer needs from those people who interact most with customers are stifled.