Unneeded Meta tags in WordPress

Sometimes in your theme unneeded meta tags show up. They look like

<meta content="noindex,follow" name="robots"/>

or something like this.
I have seen three reasons for this:

• Plugin settings. In this case check your plugins, uncheck what’s needed. Main plugin candidates: All in One SEO Pack, other seo plugins.

• Blog Privacy atributes. In this case go to Settings -> Privacy and check

I would like my blog to be visible to everyone, including search engines (like Google, Sphere, Technorati) and archivers

• Hard coded values in theme files.  In this case go to Appearance -> Editor and delete such meta tags from theme files.