Comment 8 for bug 1066108

This is a pidgin issue, which of course isn't in the default Ubuntu install. So thankfully it doesn't effect all Ubuntu users. It is behaving as designed in pidgin. Pidgin sets the default avatar to ~/.face if it exists and if you don't specify one when adding your account. The default avatar is then synced to gtalk if the avatar differs from what gtalk has.

Also of note, it has been this way since Feb 2007.

However, until recently the ~/.face wasn't getting created at install time. So often it wasn't created before users created their pidgin accounts.