Posts in Google+ search
Searching in Google+ often returns posts that have been shared with you or posts that have been shared publicly. Occasionally these public posts, while interesting, may be from people who you don't know.
The content that you share publicly in Google+ is publicly searchable – even if your Google profile isn't. The content that you share to specific people is only searchable by the people it was shared with. There's no way to make the content that you share not searchable.