IP address blocking, unless done with a bit more than random treatment, is a waste of time, once you understand the actual technology used to deliver the payloads, ie, the member signups and forum postings. Years ago I used to do such things too, it's a total waste of time, unless you do it in a more advanced way, that most generic forum software out there doesn't support.
There's 4.x billion ipv4 addresses out there, and soon, with ipv6, there will be untold billions more. You can use IP addresses as a foundation for more aggressive blocking, but you can only do that using programming, and a bit better understanding of how this stuff works behind the scenes than most forum people have, on the back end of things.
Backpackinglight is doing what they can do, they have certain limitations however, and that's just how it is.
For moderation to be used well however, you definitely need someone from each time zone watching the boards, if the boards are attracting attention from spammers on an ongoing basis, ie, fresh new signups and spam postings, and if those postings are remaining up for more than an hour or two, the spammers work is done. bpl has to decide on how they want to handle this fact, if it continues, different actions have to be taken, if it slows, different story.
Spammers are just people, usually people running software written by other people, they get paid by other people (or the spammer may also generate their own websites, it varies) who have sites that in most cases are worthless one off throwaways, or spyware traps, or whatever else they think they can pull a small marginal income from, you don't need forensics, the stuff is well understood, if you want a list of today's or this week's current fresh temp sites being marketed, I'll give you one, not that it will do you any good, there will be a new list out tomorrow. Since we don't have legal standing in Belarus, Ukraine, Russia, China, India, Pakistan, Bangladesh, or most other popular spammer locations, I'm not sure what forensics would help anyway, most spammers don't base their operations out of the usa, though some do. Most of the processes involved use the same exact technologies that the internet itself uses, software, automation, databases, some trial and error, so really all spamming is is exploiting weaknesses in the methods and software that runs the internet and websites in general.
The actual problem is more of a game of perception than anything else, spammers basically see the internet as a resource that can be exploited, the same way oil companies see an oil field/basin, or Kentucky coal mine operators see mountain tops, ie, covers for their coal, they have little emotional investment, they sell a service/product to anyone who wants to pay, like anyone else involved in marketing or resource exploitation. Spammers, that is, understand the actual structure and nature of the internet and web search and marketing quite a bit better than the average person. It's useful to understand this, these guys are just working doing what they do, like most of us. If you think of the type of spam you don't even question anymore, it might help put it into perspective: television advertising, radio ads, other media ads. Different there is you have to pay to place it, but spammers have grown to realize that there is a way to get ads up without paying, and links, and other things, that is a fact. There are also lots of ways to stop them, completely, but that requires certain things that I don't believe bpl can do at this point. Basically picture it this way, you had a jar of pennies on your front lawn, for years, nobody paid attention to it, but then one day, someone realized that it was there, and started grabbing a few, then they told their friends, then soon they realized they could just use scoops instead to grab the pennies. At that point, you can change the idea of just leaving out the jar of pennies (which means, essentially totally free and open and uncontrolled access) to something a bit more robust. Many choices. Spam is a technical problem, that has technical solutions, like most technical problems. Using endless man hours to do it manually, is not in general a very good solution though it is good enough for now in some lightly targetted forums, but I believe in the next wave of improved spamming software, forums might not find that adequate any longer.
There is an easy way however to not see any more internet spam, turn off your computer and go out for a hike, you'll find that method is 100% successful. I personally guarantee it, I have tried it repeatedly, and it works. For example, being occupied with other things, I haven't seen spam here since that last bunch that was all deleted with the new delete button, so I'd hardly call this particularly bad at this moment.