I think most of them are fine.  A few of them are of the "I must post today but I am tired/sick/brain dead" variety but those are ok, too, because we are human and that just makes us seem more so. 

I would hope that all blogs are good content blogs, but as we approach deadlines, the answer might not be what you want to hear.

One thing I do like to add, the 30 in 30 day blog challenge got me into the path of consistent blogging. And I would like to believe toward being a better blogger.

I agree with Debbie that it is both and totally depends on the author.  I might have one or two frivilous post in a 30 for 30 contests, but I write a lot of personal posts anytime and have attracted some buyers that way.  But I also see a LOT of junk posts during these contests too.

I think they do both.  But, I will say that overall, they help many develop the habit which in turn leads to more good posts. - Debbie

The challenges do encourage some poor blogs. On the other hand, most of them are fine.

Sadly, I think it generates more junk.  I know I tossed a few out there since I was so far along in the challenge and had no mental energy to come up with a decent post.

The 30 in 30 is a good contest and should not produce junk posts but the 20 a week did produce all kinds of posts.

Debbie Reynolds , I'm not sure it makes much of a difference.  And, one persons garbage blog may be another's treasure. 

They produce good habits.

I think it's a bit of a rush...

At least it forms a good habit of blogging daily.

I guess I havent read most of the posts from the contests. There seems to be a lot of junk blogs in general. I participated in one 30 posts per month contest, I didn't write junk, but I did write blogs outside my usual subject content.

most posting are out there to stay at a level. Most is trash from what I read.

Debbie,

It depends on the individual.  Do they value how they sell themselves?  If they do, the blogs will have quality.  If not, then the answer is obvious.  A

I think if a person always posted junk or listings, they kept the same type going. A few might have been "weak" but overall I think most were cute, informative or just fun. All good for different reasons.