After three months my site is still ranking for spam and non-spam keywords. 20k-50k p*rn serp impressions per month include my site (WMT). I even get link exchange requests from p*rn sites...
The spamlinks were continuously created (from March to present). The spammer now uses also autogenerated blogs/subdomains and the links point directly to my homepage in all newer spam versions.
I removed soft 404s a week ago and the content 3 months ago, but I can't see any serp changes yet.
Obviously Google isn't able or willing to detect and remove off topic sites.