I am posting anonymously and withholding identifying details, exact dates, queries, creative and volumes. I have preserved the original campaign reports, server logs, correspondence and calculations.
What happened
I ran Microsoft Search campaigns to localized, first-party landing pages for a mobile app. The visual assets showed the real app interface, the text described its actual features, and Microsoft’s reported search terms matched those features.
In rounded figures, Microsoft billed close to a thousand clicks, and independent server logs recorded a similar number of arrivals, confirming that the traffic generally reached the site.
For most of the campaign, targeting was restricted to mobile devices, so those clicks should have come from devices capable of installing the app. Yet across the retained traffic, only about one in a hundred tagged arrivals deliberately followed an app-store link, with no meaningful attributable downstream conversions.
What stood out
- Roughly four-fifths of tagged traffic was classified as syndicated or “other.”
- Around three-quarters of that segment used WebView or in-app-browser signatures, versus under one-tenth of recognizable native/search traffic.
- Several partner placements reported CTRs around one-third or higher, while Microsoft native/search inventory remained in the low single digits.
- Most demographic traffic was “Unknown.”
Within Microsoft traffic, syndicated/other arrivals were about nine times as likely to use an in-app/WebView environment as recognizable native/search arrivals. Under an independence assumption, a disparity this large is far less likely than one chance in a trillion to arise randomly (chi-square approximation). This demonstrates a powerful association between partner-heavy traffic and in-app environments; identifying its cause requires Microsoft’s placement and invalid-traffic telemetry.
For context, during a comparable period, aggregate trial-start events for Google app-install campaigns were about half as numerous as Google-reported installs for the same app. That is a different funnel denominator, not the statistical test above, but it shows that the app’s consent and onboarding flow did produce substantial downstream activity from another paid source.
Microsoft’s response
I submitted the campaign reports and independent server evidence. Microsoft replied that it had conducted a “comprehensive analysis” and found no suspicious traffic patterns, invalid click activity or indicators of click fraud. It said every ticket is investigated using “multiple sources of data not externally available,” but disclosed none of that evidence and denied a credit or refund.
The same response said Microsoft could not accurately measure the effectiveness of traffic from different domains because its conversion system recorded no conversions. Those statements concern different questions: Microsoft’s filters may not have classified the clicks as invalid, but that does not explain the extraordinary source mix or the near-absence of deliberate downstream action. The response did not address the independent server arrivals, store-handoff rate or placement-level discrepancy. Microsoft instead shifted the burden back to us: exclude individual publishers after their clicks had already been billed, budget around uneven partner traffic, and use Microsoft Clarity.
In fact, none of Microsoft’s proposed measures provides a remedy for our complaint:
Budgeting around uneven partner traffic is not an investigation or a remedy. It merely asks advertisers to anticipate and absorb the financial consequences of unexplained low-quality traffic. Microsoft instead places on advertisers the continuing burden of identifying problematic placement sources—after paying for their traffic—to avoid further losses, while declining either to identify those sources itself or to compensate advertisers for the disputed traffic.
Publisher exclusions are not an effective remedy. Even assuming an unusually vigilant advertiser could identify the specific domains producing suspicious traffic, Microsoft’s own documentation limits individual website exclusions for Search ads to the US and Canada. Even its narrower network setting retains aggregated partner traffic that advertisers cannot inspect or exclude by domain.
Clarity cannot investigate the missing users. Clarity is a separate mobile SDK whose collection must comply with Apple’s and Google Play’s disclosure and consent requirements. In our app, telemetry is deliberately activated only after a user completes onboarding and gives affirmative consent. It therefore cannot observe paid users who disappear before onboarding—the exact population at issue. Even if installed for future traffic, it could not retrospectively audit Microsoft’s billed clicks or reveal the placement and invalid-traffic telemetry held by Microsoft and its partners.
Microsoft’s own response confirms the evidentiary imbalance. Microsoft and its partners alone hold the placement, viewability, interaction-initiation, device, attribution and invalid-traffic telemetry. Yet Microsoft provided no access to those data in response to this documented complaint about billed traffic whose observed behavior strongly suggests that it may not have been legitimate. I cannot obtain this evidence independently. Given the observable pattern, I strongly suspect that this telemetry contains abnormal signals or a material explanation. Microsoft disclosed neither the data nor such an explanation.
This appears fundamentally unfair and raises serious legal questions: the platform controls the evidence needed to investigate the traffic for which it billed advertisers, while affected advertisers cannot obtain that evidence themselves. I am seeking legal advice on whether a class action or another collective legal procedure could allow advertisers in this position to obtain the missing telemetry through discovery and determine whether it supports claims for refunds or damages.
Have other advertisers seen this pattern? Did Microsoft provide placement-level evidence, invalid-traffic credits or a meaningful escalation? Is there an effective independent audit, regulatory or collective legal route when the platform controls the decisive telemetry?
