Worst yet, quite a few articles used for marketing target non-buyers. For example, the how-to article frequently used for marketing to potential clients. Just consider the psychology for a moment. If they want to do it themselves, the chances go down they are willing to hire. Moreover, if they are forced to do it themselves, it would likely be due to lack of ability to pay.
The average how-to tends toward driving low income wannabes. With the ever-so-occasional exception who, throwing up their hands in defeat, is ready to allow you to pitch them -- no way, shape or form a pre-sold rabid buyer. Most are mistargeted non-buyers, the missing part of "how to" is "How To ...Do It Yourself Without Hiring." That's the tendency.
Finally, but not least, most of these articles are general lowest-common-denominator basics available everywhere. Each article covers roughly the same, generic, basic ground ...no added perspectives, insights, expertise, niche, or differentiation from any similar article. Google bot can tell it's technically not a duplicate -- which doesn't mean that article is unique by any means.
Case In Point: The opening post. It could be a Wikipedia entry about the topic of article marketing. It's like every other opening post on article marketing ...ever. There was probably one just like it last week. And there will be another, indistinguishably identical post on using articles for marketing next week. And the week after. And the week after that one.
So, if you are not doing business with the OP right this minute, don't write articles like that expecting you'll get hungry, enthusiastic, perfectly profiled buyers either.
In other words, such articles do little to establish the client/writer as an expert, but as a "me-too." The futile hope is somebody searches once .... reads exactly one article on a given topic (yours) ....and then visits your site and nobody else's.
Article marketing can be a genuinely smart marketing move. Still, the tendency is volume traffic over quality.