As a concrete example, I found a grey area way to get a somewhat popular hardware tinkerer interested in something I did. Maybe I even skirted the rules a bit by sending him a free sample of my cool toy and some rough code samples. He took it well beyond what I could. I didn't ask for anything. The investment paid off. Aside from his initial blog post, others took inspiration and posted their own variations.
Google now thinks I'm the bomb for something very niche, but reasonably profitable. Likely because my efforts, plus other's work, netted some interesting backlinks. and backlinks to their posts. And maybe I am a badass in this very narrow niche, but I doubt Google would know if I hadn't pushed the envelope a little.