Privacy
Clicking a link tells the next site where you came from
Browsers send the referring URL by default, so following a link from a results page can disclose that page to the destination.
Guides on Privacy: Three kinds of hidden labels in one file, Who could see it, how, and what each path costs to close, Soft delete, backups, caches and logs, Sometimes, and the policy clause that says so is easy to miss
Clicking a link usually tells the next site where you came from. The browser sends a referrer header with the request; by default it carries only the previous site's origin, but a site's own policy can widen it to the full address, including any result ID in the path.
What actually gets sent
The referrer header carries the full URL of the previous page unless something restricts it, which historically meant everything: the domain, the path, and any parameters in the address, including a result ID or a score embedded in the link itself.
The W3C Referrer Policy draft now makes strict-origin-when-cross-origin the default: the full URL for same-origin requests, only the origin for cross-origin ones, and nothing from HTTPS to HTTP.
A site's own headers can override that default, and misconfigured sites still send the full URL.
A URL that encodes a result is a data leak on its own, and the referrer header is one of the ways that leak reaches somewhere else.
Who ends up seeing it
The destination site's server logs the referrer as a matter of course, the same way it logs an IP address. If the destination itself runs third-party analytics, the referrer can pass through to that company too, extending the disclosure a second time. None of this requires malicious intent anywhere in the chain; it is the ordinary behaviour of a decades-old header that predates any thinking about sites like this one.
What limits the leak
A site that sets a strict referrer policy - no-referrer or strict-origin in its response headers - controls what leaves when someone clicks outward from it, and this is a setting the site chooses, not the visitor.
Opening a link in a private or incognito window does not change referrer behaviour by itself, which is a common misconception; the header is sent by the same browser engine regardless of the window's privacy mode.
Browser extensions that strip or randomise referrers exist and work, at the cost of occasionally breaking sites that rely on the header for legitimate routing.
Rate Cock sets a referrer policy on its result pages as part of its handling of outbound links, which is the detail worth checking if this specific leak concerns you. Measure My Cock's data page covers the same header behaviour from a method-tool's session. A human-reviewed result carries no comparable link-out step in the same way; Rate Penis's coverage of the reviewed process is a different shape of interaction from the start. Penis Rater's guide to what to check before trusting a tool is where this sits alongside the rest of a site's outbound handling.