In reply to TJL (Forum Supporter) :
I've found the spamming kinda fascinating and went down a bit of a rabbit hole. It's called "black hat SEO" -- they're trying to manipulate page rank. Content in forums apparently confers extra legitimacy, which is why they're dumping it here (as well as all over other forums that they can easily post to). Also, GRM's site already has great SEO and a really good domain rank, or authority -- it's very credible, which helps the spammers: their BS rides on the coat-tails of GRM. Meanwhile, I think it's more than just the word "Quickbooks," or whatever other service they're pushing. It's the phone number, too, and if included, links. Plus the repeated use of terms, numbers, and questions.
I also think that once you see the posts in search results like the one above, the spammer has achieved their goal, and they don't care that the post has been deleted: Google and presumably other search engines have crawled the posts and applied them to whatever page ranking the spammer's trying to manipulate. But I don't know this, for sure.
It's also conceivable that a human is posting this stuff. If "Quickbooks" is altered, they'll likely use Unicode characters that look the same but are different (called "confusables" or homoglyphs) and won't be found in a search for the word. They're actually already doing this. And even is you use code that finds them, you can have multiple Unicode characters put together form a single letter, e.g., in some instances, you can create an accented letter by combining two unicode characters. So, it's hard to find them.
It seems the best common element to search for is phone numbers, which, for now, are *mostly* (but not entirely) using standard numerals. All that said, I assume this is a big enough headache for people that there's a tool, or equivalent resources, available that can search for at least a majority of confusables, though you probably wouldn't have to: if a post has more than, say, 10, it's a baddie, and nuke it.
TL;DR Search new members' posts for phone numbers, and don't publish, if found.