We have even defined links as good based on pagerank or relevancy. Some have claimed that link spamming in Google's eyes is based on diversity etc
Though some of this matters its no longer how spam is defined by Google. Over the last few days of having people show me their links and looking at my own and how the serps changed its no longer viable to talk about these category of links as what defines a spammy link. You can have a network full of PR5 sites and pages and still have your links dinged by an algo as pure spam
Spam now is simple and more direct
ITS ANY LINK LEFT ANYWHERE surrounded by either no significant content, no relevant content or junk content. Its anything, to use the phrase that Google has over the years, that is not a good "editorial link"
Good editorial links IT TURNS OUT DO have a footprint
- The are not surrounded or on the same page with scores of other editorial links
- they are not on sites that have little or not content (seriously who writes a one page article on WP links to a page and calls it a day for the whole site?)
- they have some surrounding related words
- the sites the links come from on the whole are about something not about anything or nothing at all
and there are more that you can probably add.
That means not getting forum links or blog comments or profile links isn't that big a deal. YOU CAN AVOID THOSE AND STILL GET DINGED. I have seen people put links on high pr pages and get hit by the last algo.
All of them have one thing in common - the content on the sites linking to them was garbage, even spun content and some with next to no content - some just dropped links on pages and called it a day because the pages were pages with PR. Others did 100 -150 word and slapped the link on. They ALL WERE ABOUT NOTHING OR ANYTHING as an overall site.
Unfortunately some of them were even my own customers who listened to me when I talked about high PR domains but ignored me when I said stop spinning, and save some investment for content.
Why did they do that? Because content takes finding a good writer. or lots of time, or several 10+ dollar articles per site and marketers don't want to deal with that.
Content is the quality link builders greatest pain in the neck and no spinner, or scrapers, be they WAC, KontentMachine, SEO content machine, Spinrewriter, Word AI or scores of others has solved the problem or will anytime soon.
Content is the footprint Marketers just can't help but leaving and content is why your cheap link provider is your worse enemy. He/she cannot afford to have that content produced. He cannot automate that kind of content. He cannot scale it with automation tools
In other words he/she cannot avoid providing you with what will eventually (or now) not rank you - but will even tank you in some past, present or future algo change. Content for hundreds if not thousands of clients is beyond their capability to create in any quality and maintain the prices you wish to pay and they wish to charge.
SO the truth? You now need to control not only the content on your site but you also need to control/ ensure the quality of content around the links to your site regardless of whether its a PBN, natural organic or web 2.0s.
Simply just avoiding kinds of links isn't enough anymore. If you are not willing to pay for better content then get out of the game or go entirely white hat. If you are a service provider then put money away for a retirement if you can't or won't up your content game. Your customers will eventually cry you out of business as they get tanked by each coming algo.