When I do and don't read a blog's comments
I read (or sometimes skim) a relatively decent number of blogs, and as someone who writes one too I wind up noticing various aspects of the experience. One of the things I've noticed is that I am both quite predictable and quite divided about reading comments on entries; there are some blogs where I always read the comments and there are a lot where I never do, but there are almost none where I sometimes read them and sometimes don't.
In thinking about this, I think that there are two determining factors. One is whether or not the comments 'add value'; whether they are interesting, informative, amusing, and whatnot. The other is whether or not the comments are a conversation, where the original author also comments; if the original author doesn't reply to comments, what you have is just a stream of reactions to the entry, and if I wanted that I would trawl the blogosphere in general.
(Partly my bias is because I find most comments to be less well done than actual blog entries, which is not really surprising, all things considered; I feel that most comment writing environments are not that conducive to good writing. It's sort of like dashing off a first draft email message, usually under time pressure, with a bad editor to boot.)
Another way to put this is that if I wanted to read other people's writing in general, I would be reading their blogs. Thus, if all the blog's author does with comments is give other people a convenient forum, I'm pretty much not interested.
(The exception that proves the rule is if the original entry asks a question that I'm interested in; then the comments hopefully provide a convenient collection of answers.)
PS: none of this should be taken to imply that I don't read comments on WanderingThoughts. That's a different situation; I am always interested in people's reactions to my own entries.