Oh, I'm so embarassed!
I can't believe I fell for that d*mned spammer! He's been doing this for the last few months, randomly taking some text from a posting and re-posting it. It fits into the topic, so one doesn't realise it's spam for a while.
The clue is always the two links in the bottom left hand corner. The postings of arros123, etc are all the same thing, as I'm sure other regular Forum members have worked out.
I've marked these postings as spam (using the "spam"-icon available on every post - the exclamation mark in the triangle), I've written to the mods via the internal messaging system of this site, and I've mailed the mods via external mail (using the address of the sender for the automatic notifications when someone responds to a posting I've made). None of this has had any effect - the external mail wasn't even deliverable.
This is a huge contrast to a few years ago, where the mods removed spam (or even nonsensical postings) without being asked.
Oh well... guess it's just someone we'll have to live with.