There are two kinds of passwords. There is one kind where you must enter the password before you can actually enter the website and see anything at all. It is completely blind. You don't see anybody's names, photos, user IDs, comments, nothing, until you create a password and go inside. That is a large portion of Facebook and medical kinds of sites where patients talk to each other.
Then there are the other kinds of passwords that are simply there, so that I have my space and my friends see what I have written, and everyone can follow each other. We know that because there is a name associated with each comment. That's the second kind of password.
Those are searchable by whatever browser you want to use, the Googles, and that's the kind of data we collect—only the data that is physically viewable if you were to go online and not have your own password.