It's important to note — no matter what their advocates might claim — these might work for a while, but it's trivially easy for Google to figure them out. (After all, their initial algorithm was built
on link pattern analysis — and that's the core of what they do to this very day.) I've been at this for 20+ years, and I can't tell you how many people have come along claiming they have some sort of "secret" that will make their network "invisible" to Google... only to learn they aren't as clever as they think they are. Turns out Google hires a lot of really
smart and talented people who are really
good at figuring thing out. And once they figure it out, it's not unheard of for the entire network to be penalized or even de-indexed.