You know that you're addicted to Heroes when you've tried out certain powers
You know you're addicted to Heroes when you've bought a red umbrella
You know you're addicted to Buffy when claddagh rings are no longer overdone and cheesy
You know you're addicted to The Wheel Of Time (book series you lot have probably never heard of, but I love them) when you find yourself mentally using swearwords and phrases from that universe.