Blogger recently simplified private blog access, and removed some of the ambiguity from the membership invitation acceptance process. Previously, an invitation to a private blog involved an email message with several options. Besides the expected invitation to join (using a Blogger / Google account), one might find an option to "preview" the blog, and / or view as a "guest" (without requiring a Blogger / Google account). Both the "guest" and "preview" options caused confusion, for both owners and prospective members.
What Blogger won't tell you