There are two types of blogs:
a) those written by people who are experts on a topic they're writing about, and their posts can be very useful to other people who are working on similar things.
Such blogs are very informative, and have a purpose. Design looks professional, and there are not any bigger annoyances.
Grammar is good, sentences are well formed. Box on the side provides more info, or links to other useful resources on the web.
Such blogs are very rare.
b) Those mostly written by emos, teenagers who have got nothing better to do and people who think that someone actually cares about crap that's going in their lives when in fact the only visitors they have are bots and other idiots who only comment to say things like 'I like your blog', 'great post', 'please comment on my blog'.
Such blogs also have a very poor grammar, there are no paragraphs and that makes it even harder to read.
Useless blogs that are of no value to the community in any way can be divided into following subtypes:
EMO CRAP - random ranting about how you are depressed, how you saw a good movie which reminded you of past and made you cry or how you bought a new <emo band name> CD.
colors are usually dark - the banner is way too big, and shows grayscale images of converse shoes or blood.
TEENAGE GIRL - usually consist of short posts with no grammar at all, and sentences like: 'school sucks.... i went shopping today. :DDDDDDD'.
smile to text ratio is usually 5:1.
The designs of such blogs are usually crappy, colors are flashy and hard to read, big images in the background, layout is mostly broken by crappy flash apps or gif images which flash for no reason at all.
Boxes are full of guy pictures, and lists of people they like/dislike, along with their own image, full name, mobile phone number, school, town, country zip code and other info useful to stalkers.
There is also a lot of music embedded that plays when the page loads and often there are more then one songs playing at once.
IDIOTS WHO THINK WE CARE - people who think that someone actually cares about how they just bought new shoes, ended in a debt or whatever.
ONE TIME POSTERS - those who have only one post informing us that they will now be writing their own blog.
"EA just announced RED ALERT 3, yet another game in the C&C franchise, but a first game in the Red Alert universe since EA took over Westwood Studios.
No one understands me. I feel so alone. Yesterday i bought new <emo crap band name here> CD. I can really relate to these songs. ...and so on
<girl name> and I went to mall today.... :D btw, i hate school... so boooring. <guy name> is so hawt... <3
I just bought a new coffee machine and i like it because it has so many functions. I also think that this blog is interesting to visitors who are not search engine bots who have not yet been enhanced to the point when they realize this blog is crap and nobody cares about it and spam bots who don't really care about my crap, they just want emails.
This is my new blog. From now on I'll post stuff about events in my life.
"When I read about what happened last night, it made me blog all over my website."
"I thought that chick was so hot that I had to blog about her when I got home"
In the past these were used as a form of diary, where the individual responsible for the blog would bitch about their daily activities. Though often incredibly banal, this could be interesting, in a voyeuristic, and rather unwholesome manner.
The recent trend, however, is for bloggers to merely reproduce news stories that they heard on the mainstream press or other blogs, and either make a brief, badly-informed comment on the story, or link to a brief, badly-informed comment on another blog. This has led to the blogosphere increasingly resembling a gigantic, electric circle jerk.