A potential client calls and wants a website, as a web developer you are more then happy to help. You show them your work, explain how your work is better then the rest and sell the person on the importance of Web Standards. Do you think that a client wants to hear all about Web Standards? Most likely they do not. They do want to here how you are going to make there website a success.
This does not mean that Web Standards are not important or that you should not follow them and yes you should tell your clients that you build websites using proper coding. But this is what they expect from a web developer, otherwise they would be trying to build a website on there own.
A web developer should be responsible for explaining to a potential client what it takes to make a website successful before they pay for your services. Many people still believe that all you have to do is build a website and visitors will show up at your door begging to buy your products. A web developer knows better and should make his novice clients aware of this. No client should think that a website will be a success without spending money on advertising. If you do not offer advertising or SEO optimization to your clients you should be prepared to recommend companies that do offer such services.
It is very important to remember that if a client’s website is a complete flop they will put some or all of the blame on you. Especially if you did not explain the pitfalls of owning and operating a website. On the other hand if you do promote there website or teach them the ins and outs of promoting a website they will be a satisfied customer. Most of my customers are referred to my company by existing clients and I truly believe this is because we do not just build a website for them but teach them what it takes to be an online success.