You tell them apart by asking for a plausible causal mechanism and real evidence, not by counting how many people repeat the claim. A real ranking signal has a reason Google would actually use it, a mechanism that makes sense for ranking quality results, and ideally Google’s own confirmation or controlled evidence that isolates the effect. A repeated correlation is just an observed association in the data, a pattern someone noticed between a feature and rankings, with no demonstrated cause behind it. The discriminator is causal-mechanism-and-evidence versus correlation-with-a-confound, and the test is “what is the mechanism and is it confirmed,” not “does everyone say it.”

The classic giveaway of a correlation masquerading as a signal is the confound. Studies find that higher-ranking pages tend to have shorter URLs, or more words, or some other measurable trait, and the trait gets repeated as a ranking factor. But the trait usually travels with something else that is the real cause. Shorter URLs sit on better-structured, more authoritative sites; longer content correlates with thoroughness that satisfies intent. The measured feature rides along with the actual driver, so optimizing the feature itself does nothing. An association without an isolated cause is a confound, not a signal.

This is why widely-repeated correlations should not be treated as signals just because they are everywhere. Repetition is evidence of popularity, not of causation, and SEO advice propagates claims faster than it tests them. A claim can be stated confidently by many sources and still be a confounded correlation that nobody actually verified. The honest move is to demand the mechanism and the evidence before you act on a supposed factor, because acting on a confound spends effort on a lever that is not connected to anything. Consensus is not confirmation.

To apply the test, take any claimed signal and ask two questions. Is there a plausible mechanism Google would actually use to reward this? And is there confirmation or controlled evidence, or only an observed association that could be explained by a confound? Treat the claims that pass as real signals worth acting on, and the ones that fail as correlations to ignore no matter how often you hear them. Test for mechanism and evidence, not consensus.