Signs of a scanner include three or more links clicked within two seconds (R-CLK-BURST), a click from a security vendor’s network (R-CLK-VENDOR), from a cloud or hosting network (R-CLK-CLOUD, R-CLK-HOSTING), from a browser without a window (R-CLK-HEADLESS) or an automated one (R-CLK-WEBDRIVER), and a click within seconds of delivery (R-CLK-DELTA). A click from a data-centre network is never classified as likely human activity.
Signs of human activity include the page running in a visible browser tab (R-CLK-JS), a home or mobile network (R-CLK-RESID) and a click well after delivery (R-CLK-LATE). Even then the verdict is at most “likely”. The rules are versioned, so stored clicks can be classified again when they improve.