phranque - 10:14 am on Nov 28, 2010 (gmt 0)
there are countless paid and free "IP reputation lookup" tools available.
most of the information reported will apply to email spam and malware content servers.
you are probably more concerned with web spam.
if you have a dedicated IP the previous spammy domain(s) will no longer be associated with your IP.
and presumably there wouldn't be any links between those domains and yours.