Here’s a classic example for stupid “contextual” in-line ads:

Clicking on the “feature” link in this article brings up skin care products.  The “tool” link in the first line points to Honeymoon Planning Services.  Here are some more cases of “contextual” advertising gone bad:

• The Irony of Contextual Advertising
• Contextual Advertising Blunders
• The Scary Thing about Contextual (?) Advertising

But all these mishaps aside, here’s another reason why you should avoid such in-line hypertext ads:

They seriously reduce readability. This article happens to be quite important, so the first thing I’d like to do is click on the link to the Google tool that allows me to protect my account (you should read the original article to understand what’s at stake). But I can’t – the link is hijacked. In fact I can’t even tell if there is any intentional, relevant link in this post.   Blogs, wikis, you-name-it: online writing is all about linking and relevancy. But there’s only so many we can deal with: when your article becomes a link-jungle, it becomes impossible to find the meaningful ones, supporting your message.

See also: Ridiculous Advertising – or the Case of the Hijacked link