This doesn't usually happen with a blog, but something like that may happen.

You can set to either not allow comments or moderate comments and that cuts it down quite a bit.

If you have your email address published on the site, you may get odd emails, but you don't have to publish it.

But, in general, unless you're promoting the heck out of your blog, most people will never even find it. There are millions of blogs, and people who want more traffic sometimes have a hard time getting it without a lot of focused attention on just promoting.

Ishtar