When is a blog an advert?

I am arguing in ever-decreasing circles as I try and figure out what hacks me off about certain blogs and articles while others are fine.

Basically, I'm a bit confused about what is and what is not OK for a blog or an article for something like Entrepreneur Country.

Blatant, flagrant ads are a total turn-off:
"Come and buy from me at www.i-need-your-money.com". I get that.

Case studies seem to be OK as long they aren't pushy:
"Let me tell you a story with some learning points..."

Painfully thinly-veiled requests for help are not OK:
"Just wanted to ask your opinion. I run a company that needs more clients and wondered if you wanted to know more about what I do... please visit www.i-need-your-money.com"

Requests for help can be OK if the author has a track record of being a good egg.:
"Wanted: feedback - what do you think of my website?" or "in the interests of research can you spend a few minutes helping me..."

Pure educational pieces are fine. As is good quality commentary and journalism if it doesn’t have a ‘commercial’ interest or angle at the back of it.

Obviously, the clincher is if there is a blatant call to action which says BUY ME NOW.

Most blogverts are so thinly disguised that it just creates waves of disgust. They are counter-productive as they create such a turn-off for the majority. The digital equivalent of shooting yourself in the foot. If someone could be bothered, I am sure they could stratify and label the different types and flavours...

I guess the crux of the argument is based on the premise that nearly every blog and web-based article has some element of ‘sales pitch’ in it? Either it says “look at me” or it says “look at the ad just to the left”.

In conclusion, it is worth remembering what a Blog was originally - a Web log. Wikipedia defines it as "a personal journal published on the World Wide Web", and one that invites interaction or some extension of the dialogue.

That is so very different from advertising. Or is it?