Running ads on your ecommerce website can be very confusing to customers...

[mandy]

From Elastic Path's Get Elastic blog:

Running ads on your ecommerce website can be very confusing to customers, especially when it competes with the product image or resembles a customer service function like live chat...

full article: http://www.getelastic.com/bad-ecommerce-ad/

A somewhat related blog article:
Bad, Bad Ads Manifesto, Chapter 1
http://www.adlininc.com/corporate_underpants/?p=33

[Angnor]

A good observation, I assume. But at the same time, affiliate and partner links may do good in a proper context (mostly text links and descriptions in articles).

[accentnepal]

An industry leading company like eBay would never dilute their own sales like that ....


.....

[amy]

Amazon has started doing it to. 

I'll agree that the sponsored ads, and the comparison pricing listings on product detail pages, on Buy.com's site are really confusing.  Not only do they have sponsored links on the pages but they also have an "also available from these other merchants" section that lists (and links to) the item's price at offsite merchants.  The other day I looked at one of our listings on Buy and "the also available at.." section contained a link to Alibris--and the Alibris item our Buy listing was being compared to was one of our listings.