Jul 25, 2011 12:45 GMT  ·  By

Microsoft is testing sponsored search results mixed together with organic ones in Bing, a practice that raises ethical concerns and won't probably be very well received by users.

Sponsored links normally appear at the top of search results or on the side and are clearly marked as ads. So when analysts from Rimm-Kaufman Group (RKG) published a Bing screenshot showing paid links mixed with organic results last Friday they surprised a lot of people.

RKG's screenshot is of a Bing search results page for "custom t-shirts" which displays a regular advertisement on the right side, a few results from Bing's shopping service, followed by organic results, some sponsored links and more regular results.

A Microsoft spokesperson confirmed for Search Engine Land that Bing is testing the new ad delivery system, but declined to offer more details.

"We’re constantly testing and experimenting on Bing, and with that, we carefully measure user engagement and reaction to these changes. We have nothing further to share at this time," they said.

The practice, if introduced permanently, will clearly raise ethical concerns because aside from a small Ad mark in the right upper corner, which is easy to miss, the listings look the same as organic results.

In comparison, Google's sponsored results are always shown at the top of the page, are marked with "Ad," but also have a different background color which clearly differentiates them.

The news comes as Yahoo is steadily expanding its search partnership with Microsoft. The company announced last week that its search service in six more countries, New Zealand, Argentina, Chile, Colombia, Peru and Venezuela, was switched over to Bing.

It remains to be seen if Microsoft will receive the metrics it needs to make this a permanent feature in Bing as a result of these tests, but now that the news is out people will definitely keep an eye on its progress.