I've had an rough idea about implementing a ["report spam"-feature for Echo JS] [0] that doesn't require any modification to LamerNews for quite a while now, but couldn't act on it yet due to not having much spare time.
In the meantime, feel free to contact me via twitter (@sbruchmann) or mail (hi@sbruchmann.me), when there's a another wave of spam that hasn't been dealt with for quite a while. (Most recent example from today: Spam about something something Chennai)
[0] See https://github.com/antirez/lamernews/issues/117#issuecomment-379110444
Edit: Add link to issue comment.
I’ve heard about the following cheap and dirty solution against spammers not targetting a specific site:
Add visible checkbox: “I’m not a robot” and a hidden one.
Bots will either check both or none.