I just reported the message I think you are talking about with the 'Report Bad Post' button. It also makes it easier on the mods if you you include a link in your post. The Report Bad Post button does that though, and I think it drops the message into the Moderator Forum for quick identification.
Yes, please use the "report a post" function (click the little exclamation mark in a triange icon under the poster's information) to report spam. It will give the mods clear links to the exact post in question.
It is! In the past month, 272 spam threads have been intercepted before anyone ever saw them -- thanks to Michael's great "black list" spam filter. That's 272 threads we didn't have to delete, and that makes us mods very happy indeed.