* Hacked account. I actually, upon reflection, did not mind that Google shut everything down of mine when they labeled a blog as spam. What if it were spam written by someone who had hacked into my account? The key thing here is to make it very easy to prove you're you and get back in. And apologize profusely, and explain what it happened. I got everything back but the blog as soon as I confirmed an SMS'ed code. They did take more than a week to get the blog back on line, which was annoying, even if it was nothing important.
* Actual spammers would love to be able to test the boundaries and get quick feedback about what's going to work and what's not going to fly. They'll use any feedback you give them to improve their spamming techniques.
So... it's not easy. I think what pisses me off the most is that there's no appeal, no way to say "woah, I didn't do anything!"