Google's shift of free product search listings over to a paid model caused considerable hand-wringing among retailers last fall, but that didn't stop them from buying them.

According to an analysis by Adobe into the paid-search spend in retail under its management for Q4, 10.7% was allocated for inclusion in the new Google Shopping. The channel's "product listing ads" show up as image thumbnails with prices and links to the merchant sites where the items can be bought in searches for keywords that imply purchase intent like "cameras" and "boots."

As of Oct. 17, these campaigns were being run entirely through AdWords in the U.S., and Google's former practice of surfacing relevant product listings for free had been suspended.

The sample size is not insignificant. Adobe had over $2 billion in search spend in its charge in 2012, though it declined to break out how big the pie was among retailers in Q4. Clients included in the study had six consecutive quarters of more of spend data.

While Google was condemned for embracing a pay-to-play model (a practice it once rejected, Search Engine Land observed at the time) the company upheld that the changes were made for the sake of user experience. A May 31 Google Commerce blog post outlined that position: "We believe that having a commercial relationship with merchants will encourage them to keep their product information fresh and up to date."

But based on Adobe's findings, it would appear that Google Shopping was also highly lucrative in its first holiday retail season and that a Bing TV campaign dubbed "Scroogled" that called Google out for cloaking paid ads as "honest search results" fell short of its mark.

It would also appear that spend on Google product listing ads in Q4 was largely incremental, and not cannibalizing other portions of paid-search budgets, according to Sid Shah, Adobe's director of business analytics. Overall, total retail search spend was up 16% over the previous year. Meanwhile, Google's revenue from product listing ads alone was 78% of Bing and Yahoo's total haul among Adobe clients.

Mr. Shah expects that the success of Google Shopping will to Google's bottom line when Q4 earnings are announced on Jan. 22. "I think it will have a material impact in a positive way for them," he said.

And perhaps even more auspicious for Google, Mr. Shah observed that the average cost-per-click climbed 7% year over year, according to Adobe data. It's a reversal of a trend from the previous three quarters, when the rising tide of mobile searches on Google contributed to a lower average cost-per-click from the previous year, since advertisers perceived them to be less valuable and thus were bidding substantially less on them.