Fraud & invalid traffic
Traffic laundering
Traffic laundering is passing low-quality or prohibited traffic through intermediate sites and redirects so it reaches a search feed looking clean and legitimate.
Money laundering hides where money came from. Traffic laundering hides where visitors came from. Traffic that a feed would refuse, such as pop-unders, adult sites, bot visits or adware redirects, is routed through one or more "clean-looking" pages or a chain of redirects. By the time it lands on the monetised page, its origin has been wiped or replaced.
In search arbitrage the laundered traffic is then declared under an approved source and Channel ID. The fraudster buys visitors for almost nothing and sells clicks at feed prices. The honest version of the supply chain is undermined, because advertisers judge the whole feed by its results.
Red flags are long redirect chains, intermediate pages that nobody stays on, referrers that are blank or oddly uniform, traffic volumes that do not match the declared source's spend, and poor advertiser conversions.
Google counts acquiring traffic from non-compliant sources as a violation in scope for strikes. Defences: reconcile clicks received against clicks bought, trace sample journeys end to end, and score traffic quality per source. Compare traffic blending, where bad traffic is mixed in instead of disguised.
Think of it like this
It is a butcher buying condemned meat, repackaging it at a tidy-looking warehouse and delivering it to restaurants with a respectable label.
Related terms
Traffic blending
Traffic blending is mixing cheap, low-quality or invalid traffic with good traffic so that the average looks acceptable and the bad part goes unnoticed.
Referrer spoofing
Referrer spoofing is faking the information that says which page a visitor came from, to make low-quality traffic appear to come from a trusted source.
Domain spoofing
Domain spoofing is falsely claiming that traffic or ad space comes from a well-known, trusted website when it really comes from somewhere else.
Redirect
A redirect automatically forwards a browser from one web address to another, often passing through a tracking link that records the click along the way.
Traffic source approval
Traffic source approval is a feed provider's sign-off that a particular place you buy visitors from is allowed to send traffic to its search feed.
Click fraud
Click fraud is deliberately generating ad clicks with no real interest behind them, to earn publisher revenue or to drain an advertiser's budget.
Sources: Google AdSense Help: Policy violations in scope for Restricted Access Features (RAFs), MRC Invalid Traffic Detection and Filtration Standards Addendum (June 2020 update)