We do our best to make our machanot and in particular our chanichim's tzriefim pure, not in the sense that they're always spotlessly clean (perish the thought!), but in the sense that we don't allow those spaces to be used to say bad things about each other. Personally, I haven't seen so much tzara'at lately, but we all can attest to the harm done by verbal bullying, both to the bullied and the bully, and understand the importance of recognizing it and "purifying" the people and the places that perpetuate it.
So watch your words, and help your friends watch their words, to keep ourselves and our spaces pure. And if weird white stuff shows up on your skin, or red or green stuff on your house, go find yourself a kohen, two birds, a cedar plank, a scarlet thread and water from a live stream.