Lines, reporting should send a notice of a problem, then, the moderators see the report, so yes, it should make a difference.
Those forums that I moderate, I get an email when there's a report, so will check on it. I check those forums everyday and some days several times just to see what's going on. There's a few folks who report issues frequently, and if not for that, then there's sometimes a delay in response. I appreciate those reports, because people who frequent the forums, don't want to see that crap there and neither do I. I'm sure we all see enough garbage in our daily lives and we use these forums for our interests and to get away from all that crap!
I don't know what benefit it may be to those spammers, but I've found that when they can be removed quickly, they post less often.