A quick update.
After 2 more reconsideration requests (very well documented), and after having put EVERY DOMAIN inside disavow tool (according to links showed by GWT and OSE), Google is still answering: "we still see links to your site that violate our quality guidelines."
I have also made nofollow EVERY outgoing link...
No incoming links, no outgoing links => Google still see link problems. Very frustrating.