Don't use media that relies on it when you're not the one managing it. These features are cool when you control them. Digital signature verification on Redhat is great.
Even if you are managing it, you should still avoid it unless the hardware is designed so that it's inherently impossible for it to be used any other way. Otherwise you're financially supporting the problem.
This is the "security" people try to sell you with secure boot mechanisms and signed software.
Don't use media that relies on it for your own sake.