I though it was curious all the varied ways it was done so I've collected a few samples.
BLACK BOX REDACTION
This is one of the most common. Neat black boxes over both profile photo and name.
BLACK MARKER
This method is a bit sloppier, but accomplishes the task. In the same family is the black marker, but leaving the profile photo showing.
BLACK REDACTION AND MARKER COMBO WITH TITLES
I think with this method, the user starts with the black redaction box and then has trouble covering up all the text, so they drop down to the brush tool. As a bonus, the user included titles so that we could tell who was saying what, seeing as that you can't once all the names and faces are blocked out.
WHITE REDACTED BOX LAST NAME ONLY
The cousin of the BLACK REDACTED BOX
WHITE MARKER 50/50 FACES
The user felt obligated to hide the identity of some faces, some names, but left some names and faces visible. Very sloppy.
PIXELATED
This is a very clean method. The faces are hidden, but you can make a connection of who is saying what as you scan down the photo.
STATIC
I like this one.
RED REDACTION WITH TINY FACE REDACTION
This one is very detailed because instead of just blocking out the whole profile, they just hid a little of the guy's face.
BLUR
I assume this is the smudge tool. Dies a good job of masking without being obnoxious.
COLOR COORDINATED REDACTION
With multiple people in the comments, this person used color coordination to distinguish who said what. Very clean. Good work.
PINK AND RED SPRAY PAINT
This is definitely a MS Paint job. Sloppy, but they tried to color coordinate.
PINK BLUE AND SOME WHITE TOO
Hard to tell what is going on here. Did the poster try to suggest that the pink person is a girl and the blue is a boy? In addition, the white redacting over the names is very sloppy.
WHAT THE FUCK
I'm not sure what to think here.
BONUS
I was poking around for some others and there is a whole section of failblog.com that features these called Failbook.
I saw this neat one over there with color frames
