What is the appropriate format for reporting such activity?
Unfortunately, the number of such accounts is increasing day by day, and I do not think that using negative trust is an appropriate option.
As I see @Lafu already made a thread about Malware here: Topic: Report Malware and Suspicious Links here so Mods can take Action !
Back in the days when the Topic was started we have written there a post with Accounts that spamming the same things and links.
Once you have made a post there then you can take it as reference for future reports with the same Links.
If the spamming will be getting to much about the same Link you can ask a Global Moderator for maybe ban them.
Hope this helps you for reporting them right and get rid of the spammers.