Seriously, why isn't there a color system like this in place already? What a great idea

Maybe it means the dog isn't friendly towards other dogs but maybe it's friendly towards people?

My dog has gotten that way in her old age. She doesn't like young whippersnappers sniffing her butt anymore so she gets a little growly

I think these would be great for some people to wear, too. They would make a great conversation starter.