@Leosghost, it's all speculation. Google doesn't hand out booklets to webmasters about what not to do or what the tipping point is for penalties. Sure, quality guidelines is what they offer.
The thread is about what qualifies to initiate a human review. Google didn't tell us, so it's speculation. People post here and speak with their own knowledge and experience regarding Google.
So regarding this thread, it make sense to me that a flag might be sent up regarding many websites using the same account. If one is spam or thin, wouldn't it be within reason to assume that other from the same account might be?
But to anyone reading, understand one thing. I realize this is slightly off topic, but if you are dabbling with many multiple sites, be fully aware of the chemicals you're mixing. It's fragile. You can never assume that you are outsmarting Google by being sneaky about it. The fact is, if you push the envelope too hard, you will wake up with you sites, yes sites, wiped off the face of the internet. Ask yourself then, was it worth it? Take my word for it. Then moving forward you must ask yourself if Google has a record of your history and looks at you differently from that point forward.