@glakes Just seen your post. We're ecommerce and seeing exactly the same thing. Volume of traffic from Google organic *and* paid is unchanged, but the quality is completely dreadful and it's all barely converting, including paid. And we're also getting traffic from other countries. And it also started weekend of 18th Sept.
The weird thing is our pages per visit, avg. session duration, bounce rate, etc are all relatively stable apart from a slight decrease in session duration from the middle of Sept, so it really makes no sense. If Google was funnelling genuine but crap traffic to us, I'd expect to see some more obvious changes in those stats.
Because it's affecting Google paid (Shopping) as well as organic, I'd assumed it was just very unusual seasonal changes, but I guess it could be Google doing something across all its channels. Although that surely makes no sense with paid. You mention that maybe this is Google trying to get advertisers to pay more, but if clicks don't convert, the correct response is to *decrease* the bid not increase it. So the more likely outcome of this is Google will *lose* money. If Google is channelling the good traffic somewhere else, then someone else would be suddenly seeing an improved conversion rate, but I don't see anyone posting about that. The only evidence is from people who are seeing a poorer conversion rate.
Google are on record for saying that the conversion rate on paid clicks remains relatively constant irrespective of their position in the results, so assuming the same type of products are being clicked on, there is no explanation for why the value per click would legitimately drop even if positions were shaken up a bit.
Something else to consider is that Google Shopping changed its feed spec in mid-Sept, so many shops may have tidied up their feeds, hence increased their quality score, leaving the others behind. However, as per above, this should result only in a lower number of impressions and clicks to you, not a lower conversion rate.
So, based on the above, the only possible explanations for this seem to be (1) a genuine seasonal change in user behaviour, (2) a genuine change in who is using Google or how they're using Google, (3) Google deceptively creating zombie/bot traffic to paid in order to charge for fake clicks, (4) technical issues where the wrong paid ads/products are appearing and getting curiousity clicks that don't convert or (5) something else. I doubt that it is (2) as there has been no Google UI change. I'm sure everyone will jump at (3) but I do find it very hard to believe that Google would do this or need to do this. Google is plagued with technical issues so maybe (4), although I'd have thought this would be more noticeable. Although we currently have a call in with Google paid as some data recorded is definitely wrong so we'll see how that goes.
But most likely (5). Any other ideas?
Google Updates and SERP Changes - Sept 2015
