If you work in a marketing environment then you may need to also offer sales advice. You may find that you actually become a consultant to a business in terms of their business sales tactics, as the marketing and the sales are linked. If for example, you are marketing a business and finding that you are getting the traffic to their website and converting the visitors in to enquiries but these enquiries are not converting then you may want to spend some time investigating this process to see what happens.
If the prices of the products of services are higher than you anticipated and they cannot lower them, it may be that the traffic coming through to the site is not qualified. For example you may be marketing the phrases cheap and low cost rather than quality and bespoke. Seeing through the whole sales process and having a good background knowledge on the company will help you best advise them on their marketing.