Subscription sites may want to readjust their budgets for paid search soon.

The Federal Trade Commission (FTC) just sent letters to the major search engines, warning them to distinguish between natural and paid search results more clearly.

The crux of the letter requires search engines to “select hues of sufficient luminosity to account for varying monitor types, technology settings, and lighting conditions.” In short, the pale shading most often employed by search engines is considered insufficient for meeting the FTC’s original guidelines. Instead, the FTC recommends search engines use shading with a clear outline, a border, or both, on all paid search results.

These new guidelines are likely to decrease paid search traffic and conversions for subscription sites, as consumers will now be better able to distinguish between the two (and assuming consumers really do prefer natural results to paid ones). But at the same time, the new ruling will bode well for sites that have previously ranked high in search results but have not been able to afford or execute a worthy paid search campaign.

The FTC also reminded search engines and large companies that they are required to make sponsored results known when using alternate technology, such as mobile or voice-activated results (i.e., Siri) or search engines through social media platforms, like Facebook’s Graph Search. And the FTC said that ads should have text labels immediately before an ad or in the top left corner of a search box.