No one knows for a fact exactly how search engines work except for the engineers who develop them and I imagine most of them only understand the piece of the puzzle they work on.

SEO’s who state things as fact make me nervous. I usually pay attention to the bloggers who say things like, [This] is what I’ve been doing and it seems to be working…

SEO is such a moving target. Most of the best posts seem to be on one of these topics.

“[This]seems to work better than [That]”
“Look what I just made/found!”
“Don’t waste your time doing [This] or [That], it looks like it stopped working”

Almost nothing should be reported as a fact unless you’re talking about something that was posted on an official Google blog. Even then, the focus of the post should be what your opinion is of the new fact.

I am not an SEO, and even when a friend like Michel Fortin links to me saying I am an SEO Blogging Expert, I immediately post a comment denying the well meaning statement.

For me SEO is about testing and tracking. When I blog about SEO I mention what I am experimenting with, and the kind of results I get. There is no claim of authority, and I suggest people do their own testing.

The problem with or for “Professional SEOs”, and I mean that in regards the profession and not their level of skill, is that they are working with client sites.
It is much harder for them to blog about things that are experimental, because quite often they are working exclusively with client sites, and it is hard for them to do things that are not proven.