Designing your brand's logo? While the creative process should be free and unlimited, businesses need to be aware that some colors are heavily associated with existing brands, and using them in signage and logo graphics could be an accidental act of infringement. It sounds silly to outsiders, but legal action has been fought over businesses that use specific shades.
For example, the Washington Post recently reported on a case where the AT&T-owned Aio Wireless was ordered to stop using a color that too closely resembled the chosen hue of rival T-Mobile. In its ads and commercials, T-Mobile often employs a bright magenta color that it asserted was so important to their identity that Aio's advertising would have confused consumers.
The source notes that the particular color in question, Pantone 676C, isn't technically the one that T-Mobile has trademark over, but it was still deemed close enough to be a threat to their business.
A Business Insider article from 2012 has more examples of famous colors that are tied to one specific business, from Target's red to UPS' brown to Home Depot's orange. It's important to know the distinction between a company that actually owns trademark of a certain color and those that are simply well-known because of one.
In Australia, for example, BP recently attempted to trademark its shade of green and failed to do so. That could mean that despite the distinct connection between that green, Pantone 348C, and the brand, a company could conceivably use a similar color without legal response.
But it's better to not risk such conflicts and instead develop vinyl signs with unique images. Businesses with access to custom sign and logo makers will be easier for their target audience to identify.