The word there is trying, and can never be proven,
If there was a way, Black Hat or whatever that person who can manipulate the serpes that way would be a very wealthy person and totally control that Niche or whatever niche they wanted to be in.
I do agree though from this thread alone that Spammy links are causing this issue at present but from what i have seen from what i have seen its only been Very recent, and from the amount of feedback where sites and niches have totally been shaken up, it will be reversed at some point.
External links out of your control should not be able to hurt your site.
I took a look at someones site after they dropped last month and their SEO was totally built on these ALN, Linkvine and blog packages 500 links worth in a small geo targeted site first page for many local keywords, these links get taken away and devalued no links rankings plumet down, people shouting penalty but its nothing of the sort all it is that blue widgets in London value for that site has disappeared, because the link value has too, i bet 80% of these sites would recover with some genuine decent quality links in their place.