bbPress.org

I have a wild guess. Looking at line 79 of bb-includes/akismet.php (in 0.80) shows this:

'comment_author' => get_user_name( $user-ID ),

and I think it’s missing a > between $user- and ID

'comment_author' => get_user_name( $user->ID ),

If that fixes it, I can file a trac ticket.