There are many people sharing theories, guesses and even some blatant lies about negative SEO. This thread is not for those people. This thread is only for people that have personally faced negative SEO (either giving or receiving). If you faced a confirmed case of negative SEO please answer these questions:
How many sites have you personally seen that were hit by negative SEO?
How fast did it happen?
What were the early warning signs?
How did you prove it was negative SEO?
Was it reversed? How? In what timeframe?
Let's keep this focused on productive information and stay away from the hype