Much appreciated, and you seem a fair person. But this level of spamming is too minor for Google to deal with. You people like to deal with this at the algo level - and the algo(s) is (are) the problem. It is deliberate borderline spamming on his part, but unfortunately the serps now seem to be full of it.
I have reported this site before, twice, through the 'usual channels', but now that he's removed his hidden text, there's little anyone can do - he is just playing the algo for all its worth.
My point is that his little 'tricks' shouldn't be working in a sophisticated algo. He also uses bare URLs as links, containing keywords. Once again though, not exactly 'hidden' - just way off the bottom of the page, where no-one will ever scroll down to.
Your problems with the algo appear to be links based - I do wish you would sort it out.
Thanks for your concern anyway :)