[mkjones]

We have that: http://mkjon.es/friend.png. In addition to data from that, we also look at how many people click "not now" when someone adds them as a friend.

These signals (and a number of other factors) are taken into account when classifying if friend requests are spammy / malicious.

(I work on the anti-spam team at Facebook).

[michael_dorfman]

What is the difference (in practice) between clicking "not now" to an unwanted friend request, and simply ignoring it?