If you are putting contextual advertising on a page the aim of the content shifts from being simply a quality answer to a quality answer plus encouragement/reason to click an ad link.
Shift from teacher to teacher-salesperson. A good sales pitch can educate while it sells. And up-sells. And re-sells.
What seperates 'smart pricing quality content' from 'quality content' is presentation designed to convert as well as inform.
I would paraphrase oddsod: ...the way to make more money is to concentrate on conversion potential when writing quality content?
ronin is absolutely correct. But also misleading.
From a straight ROI viewpoint quality traffic is converting traffic.
Quality - well researched, useful, original information - content may convert, or it may not. However, in the context of this thread the definition of 'quality' content must also include its conversion rate.
If you have no interest in conversion, you have no interest in contextual ads. Once the ads become part of the page, they become part of the content. ROI becomes a quality content factor. To leave conversion or ROI out of the definition of quality content in this context is misleading.
The traffic won't convert if the content doesn't make the sale.