Rather than open a new thread, the best way to report spam is to look on the left at the very bottom of the post. There is a triangle with a ! in it. Click that and and in the box that pops up, tell the mods what the problem is with the post. Spam, people arguing, whatever. Then click "report post." This sends a message to all the mods, both in the mod room and an email.
This can also alert them if there is something in your own posts that needs to be changed but it's past the time where you can edit it yourself. I did that when I was running a recent mystery. Use it sparingly for this purpose, though, only for things that really matter - like you've told people to cut something at 3 1/3 inches instead of 3 1/2!