Each SCBL page includes a "listing history" for the IP address being looked up. The history contains the date and time of all listing and delisting for that IP address for the last 30 days, regardless of whether the listing was valid or mistaken. There is no indication in the history whether the listing was valid or mistaken, timed off or was a manual delisting.
One also has to remember that IP addresses change hands. Many ISPs assign IP addresses to customers dynamically, so addresses are changing all the time. Customers with fixed addresses may also be moved between addresses, and complete blocks of IP addresses may be reassigned, so that users end up with IP addresses that have a listing history they have nothing to do with.
The listing history is just that, a history. The current user of an IP address should not be considered a spammer just because there are previous listings shown for their IP. The listing could have been directed at a different person, a different company or the result of a mistaken report by a SpamCop user.
The SpamCop Blocking List history should be used as a small item of interest in a larger investigation which includes, but is not limited to, lookups at spamhaus.org, spews.org, the usenet group(s) news.admin.net-abuse.* and other forums, maillists, publicly accessible blocklists and search engine results.