Hi, Linda -- I think this is a really good point and a good question. I am an expert in blogging only to the extent that I write the Work It, Mom! Blog here and we have bloggers writing for us, but I do feel that a blog related to your business will drive more valuable traffic than a blog that is about something else.
I think of it this way -- I really love stationary (my husband would say I am nuts about it, but you know, that's his word
-- and I've always wanted to blog about it, to explore different kinds, stores, etc. And I am sure if I did it and really worked to grow the blog, and it had a link to Work It, Mom! some people would click over. But it would not be targeted traffic -- many of them might not be moms or even women who would appreciate Work It, Mom!.
I hope that made sense -- 2 hours of sleep last night is not helping today