Cloaking

Cloaking is serving one thing to a search engine and something else to the person who follows the same address: the crawler is recognised and given a page the human visitor will never see. Every major search engine publishes rules against it and treats it as deception of the index rather than a clever technique, with demotion or removal as the usual consequence.

The line worth drawing is between deception and routing. A link that opens a German page for a visitor in Germany, an app store for a phone and a desktop page for a laptop also returns different content per request, yet everybody was promised the same thing and everybody receives it, in the form that suits them. Cloaking inverts that: what the index is shown is not the offer made to the reader.

The practical safeguard is auditability. When traffic rules record which rule matched each click and where that visitor was sent, what a link actually does can be inspected afterwards rather than taken on trust — by the person who published it as much as by anyone else.