Every blog has good and bad, pretty and ugly, and noble and ignoble features. If a blog provides quality content, I’ll probably ignore its less wonderful aspects, but things get worse when a blogger almost completely forgets the usability of his blog and does whatever random things come to his mind.
Admittedly, what may seem annoying to me, may leave a pleasant impression on you, I believe most of you will agree with me on the following top 10 annoying mistakes some blogs make.

Have you been putting a lot of your time and energy in some posts and only a tiny fraction in others? If so, you are reducing your blog’s value bit by bit.
Here’s why you need to craft each and every post with great care.
See your blog as a package with each post as its feature. One bad post means one more feature that adds to the bulk of your product but nothing to its usability, and overall value.
Now, since you update your product regularly you increase its value with every good post and vice versa. As your product evolves and gets bigger, the value of your product is determined by the total value of all posts you made on your blog. If the sum of valuable posts is greater than their valueless siblings, you have done a great job of creating a valuable product.