I'm not going to mention poor spelling or crazy designs here. If that is a blog's only fault, I think it's too small of a fault to completely drive away a reader like me.
Too many giveaways.
...of stuff I don't want. I won't enter a giveaway just to enter. I will enter if I already really like that particular blog or that prize being offered and if I perceive the giveaway as possible to win (i.e., not already 26,000 entries). But if a blog is all giveaways, that's just overwhelming--give us a couple funny stories to read, that's what I want!
This is a case of like attracts like. I'm not interested in constant mentions of 'popular' tv shows, celebrities, 'the latest' in summer fashion, and 'desireable' brand names in real life, and I'm not interested in such things on the internet, either. I'm not a trendy person, that's all.
As much as we claim that blogging is about quality writing--it's also about personality of the blogger. If I come across a blog which has great content--and I read, and read, and read, and comment, and comment, and comment, and join a link up or two, and the blogger never responds to a comment, I'll probably lose interest eventually, because the blogger is so unresponsive that I can't sense that I'm getting to know a real person behind the blog.
Funny how those are so often the same. "Being real" and writing about something really hard that you're going through is completely different from an overarching theme of "poor me" and angry bitterness. If I come across a blog that consists primarily of complaining about in-laws, spouses, jobs, money, children, etc., I won't be inclined to read it. I'm sure such blogs have an audience, but I personally don't find constant complaining either relatable or entertaining, so I don't read them.
Too much like a product review blog.
This is probably a given. I don't trust product recommendations from people I don't know. I probably will trust the rare product review from a lifestyle blogger that I've been reading for a while, because I feel that I "know" that person well enough to have a little faith in their opinion. Blogs that are purely or primarily built on product reviews don't entice me because I don't feel that I know the blogger well enough to care about their opinion.
What do you think about lifestyle bloggers writing product reviews? What will cause you to decide not to read a blog?