It means someone is paying attention. When introducing the topic, it's more effective to say that electricity has 2 charges while chromodynamics has 3, and let them discover that those numbers are using different units for "2" and "3" only after they decide to find out more.
Carefully qualifying every single statement causes people to stop listening, because they don't care. It's better to correct oneself after-the-fact. Make it a topic of discussion once people are hooked. Introducing a simple error for someone to unravel does that.
The quarks and gluons can be red, blue, green, antired, antiblue, or antigreen.