You do, actually. It is one of the core skills in building B2C websites, since a) you'll typically want your user to take some action that requires trusting you, like putting in their private information or paying you money and b) at B2C scales, one-on-one human interaction with all users is typically neither possible nor really desired. If the website doesn't inspire trust, the business is pretty much doomed.
For example, for my site, I take pains to make sure the language I use matches the language my customers use, that the graphical design communicates professionalism, etc. If I don't do this, they'll lump me in with all the "scam artists and viruses on the Internet."
This fundamental truth might be a good thing to learn prior to investing in or advising Internet businesses. Just my two cents from a very, very small B2C business.