How do I detect spam from among published comments?
I use a view, that shows me 200 comments at once with their body. So by quickly looking at the list of the comments, I can see which are span and checkmark them to delete.

You can copy this view from the gist here: https://gist.github.com/timonweb/5990901

Make sure you have Views Bulk Operations (https://drupal.org/project/views_bulk_operations) module installed, then import the view from the gist and go to: http://yoursite.com/admin/content/comment/moderate.