It is the search engine’s definitions of black hat that is important. I don’t have a definition because I am not a search engine.
As for natural links all being relevant. Why would anyone create a link to someone else’s site unless it were relevant in some way. If you don’t think all natural links are relevant then your definition of relevant is too narrow.
anything that is restricted by nofollow is traffic
anything that is restricted by follow is ranking
anything that is restricted by none is plain (SE) crawling
So you can state categorically that links from what you call ‘black hat’ sites are ‘worthless’ but you can’t actually define a black hat site. This would be useful for you to do because we’d all like to know why google would ‘totally discount links’ from these sites.
Can you give us an example of a link that would be ‘totally discounted’?
I see, so you’re basically using the word ‘relevant’ with such a catch all meaning that anything you say using it will most likely be correct AND, given that you’re asking a question, this is just a theory you have about relevant links and you don’t actually have an practical experience in link building?
I juts want to know with what authority you’re making these definite statements Stephen, do you do SEO for a living?
Do you work for Google? If not then you are in the same position as everyone else who doesn’t work for Google in not knowing what Google consider to be a black hat site that they are going to ban from their search results.
The goal Google and the other search engines have in presenting search results that match what people are actually searching for so if they wanted to they could define SEO as black hat since it has the potential to change the results from what people are looking for to something closer to what those particular site owners want. Those doing SEO to try to manipulate things are just lucky that the search engines haven’t perfected their algorithms yet because once they finally get it right they’ll be presenting the desired results despite any attempt to manipulate them through SEO.
The only sites I do SEO for are those I develop since it is impossible to do SEO properly unless you have control of the site content since 90% of SEO is getting the content right (at least it is for the types of sites I develop, I know the types of sites you deal with are ones that require a lot more off site work).
The only interesting exception I’ve seen is that Yahoo Answers are supposed to be no follow links. Yet some of my answers show up in my Google Webmasters tools. So perhaps it’s not all that cut and dried.
Because they think the other page is:
Interesting,
Informative,
Funny,
Crazy,
outrageous,
grotesque,
etc, etc.
and they just want to share it with friends and visitors.
For linking out, the only criteria or “good reason” according to Google, is
if I think the URL has some sort of value to my visitors. Imo, that value
does not need to be relevant to my site or to my page; just “of value” to
my visitors.
I think this is why we see so many of those SHARE THIS buttons, I know
it’s not a link as we are talking, but, sharing URLs is what makes the world
wide web go 'round and 'round, imo.
Bompa
I think that the original question has been already answered so I’m going to give my humble opinion about the discussion that is going on.
Black hat SEO definition: anything that makes Google earn less money than what it could do with white hat SEO.
And according with the relevance question, definitely Google robots are still far from knowing what could be relevant for someone. Robots only care about the comparisson criteria that they have in their algorithms. There still is a long distance between what human relevance means and robotic relevance means.
Actually, what I think it’s a good a subjetc to discuss is to try define accurately what relevance means to Google. That would help us to get better SEO works done.
Oh come on Stephen, ‘do you work for Google’ is the cry of every SEO ‘expert’ who can’t actually prove their point. Besides, I’m asking YOU for a definition of black hat, the one you used to state categorically that would cause links to be discounted. Are we going to get a definition from you to support your statement or are you just going to continue to avoid the question?
That’s only the point that I’ve been making for about 2 years. Did you get there all on your own? Something good came out of this discussion then.
Contradicted by:
Oops… 
You don’t actually do SEO do you Stephen, you have such amazing content that the links roll in and you think that’s SEO.
I believe nofollow links are useful for SEO to keep a balance between the nofollow ones and dofollow so that a link building campaign will look more natural for SE. Am I mistaking?
Google no follow it, it not help google SERPs ranking but it still useful. For your question, it really not useful in SEO with Google, not other SEs
Yes, you are mistaken.
All links are useful for seo the more you have the better you will do. Its a numbers game, if the site is unique and has content that can’t be found elsewhere a link from that site may prove useful to attain additional attention from google or other search engines.
My experience is that nofollow links could increase PR, such as blog comment, if you leave so much comment, your website pr will rise to 3 from 0.
Since nofollow specifically tells Google to ignore the link for PR, you are obviously mistaken. If you have a billion nofollow links to a page and no other links to the page then you will still not have a PR for that page. Only if people follow the links and add more of their own without the nofollow will you get any PR through having nofollow links.
Nofollow links also useful in driving traffic to website
If they were not then there’d be no point in having them as that is all that they can do.
They do need to be reasonably relevant to the page they are on though or they will not do that either.