Two weeks ago, I was reminded through an error on my part just how important it is to do two things:

Throughout September, one of my sites was beginning to underperform. The overall conversion rate had dropped a little, and the cost per acquisition was rising. On investigation, I pinned it down to a particular adwords campaign that had started to perform much worse than previously. Quality Scores had dropped to 3-4 (from 7-10) – now I know that Google had some problems with their quality scores recently, but the degradation on this campaign was much worse than elsewhere on the account.
The other thing that had deteriorated significantly was the Click>Registration conversion rate. From 14%, it had dropped to 6-7% (and even to 5% on bad days!). But the quality of those registrations was still high (converting well to paying members!).

Finding the problem

I spent the next few weeks completely puzzled by what had caused this problem. Were the ads pointing at the right landing page (I checked within AdWords and they were)? Had the consumer changed their behaviour? Were the broad terms in that campaign now pulling in irrelevant search terms (they weren’t)? Had the position of the ad changed, affecting people’s desire to register (it had, from 3.6 to 4.1, so I increased bids to get things back to 3.6. All that did was increase my CPR further!) Had something changed on the landing page (it hadn’t – the landing page was one of my best performing ones)? Had users’ perception of the landing page changed (I did A/B & multivariate testing…the one there already was the winner, so it wasn’t that either).
I’d also launched some other complementary campaigns at around the time things started going south. So I paused them to see the effect (if any) on the ailing campaign. Nothing, except I lost traffic.
I then started looking at the ads that were being served. I always have 3-4 ads in each ad group, so I tracked back to see if the ads served had changed in any way. Nothing had changed.
I looked through the Change History at around the time things deteriorated. I couldn’t see anything of any importance which would be having this effect.
I was stumped. And the poor results just kept coming. Day after day, 6-7% conversion rate, and high CPRs. I got to the point of toying with stopping the campaign altogether, as it was becoming unprofitable.
Then, I did something very obvious. In desperation more than anything else, I clicked on one of my ads, just to check the ad was pointing at the right page.  The ad took me to my site’s homepage, rather than the proper landing page! I was baffled. Checking those links was the first thing I’d done within AdWords. How could those ads have changed the destination url?
Going back into AdWords, I immediately found the problem (wrong destination url on a number of keywords in the campaign, which were over-riding the ads’ destination url), and rectified it.
That very day, my conversion rate sprang back up, and past the 14% mark. I still don’t quite understand why those keyword destination urls changed in my account (I still trying to find out), but it did teach me two very valuable lessons:

  1. People who send PPC traffic to their homepage are flushing money down the toilet. My homepage (I now know!) converts quality leads at 7% – nowhere near good enough for me to stay profitable
  2. I wasted six weeks because I didn’t do the obvious thing. Click on one of my ads and see what my visitors see! No amount of “drains up” analysis got me to the correct answer. I wasted time and money forgetting that maybe there’s a simpler solution.

I over-complicated things, but you know what? In the end I’m glad I did.
…oh, and my Quality Scores? They bounced right back before the end of the following week.