As I understand a lot of people that practice black hat seo have been hit by the unnatural link building penalty causing huge serp decrease across entire domains and as of yet nobody has recovered from the penalty. Am I right in thinking nobody has recovered? Do 301 redirects work temporarily? If so can't you just put another redirect in place? I would like to do some testing on a domain that has this penalty in place therefore please let me know if anyone would like to work together on this.