As my erstwhile colleague says, this is a continual war; spammers are always seeking to exploit breaches, etc. There is actually a significant spam protocol on FlyerTalk; much of the spam you actually never see because of it. I'm loath to discuss too much of it, because spammers do try to find shortcuts all the time.

1) Considerable spam gets intercepted and trapped by automated scripts and filters.

2) Quite a bit of spam that gets through is held in a moderation queue so moderators are notified and must approve (or otherwise handle) the post(s) in question before you get to see it.

3) The tip of the iceberg is what you see, and it's easily disposed of by using the "Alert a moderator to this post" function (or otherwise contacting Admin or moderators).

So, yes, IB is working (quite well) to control and prevent spam.