hi, i am newbie in here... i want to ask about dummy blog... what is the purpose to have a dummy blog? and how much it must be? it is dummy blog must have same niche?
You must be referring to auto-blogs, right? If so, their purpose is to spam the web with duplicated contents ripped from other sites.
Maybe you mean a test blog. I use one to test any changes (formatting, plugins, etc.) before putting them on my live blogs.