Originally Posted by Collabora
This is false
Reallocation of an IP does not clean up its bad reputation. Moreover the one IP may be part of entire block of IPs with bad reputation. Thus, advice “You do what you want, if you get blocked it’s your fault" is inappropriate since the guy who had that dedicated IP before you may have followed that advice. A lot of ISPs but a lot of weight on domain reputation these days -- in that case it doesn't matter what IP you have, and if you have a good domain reputation "you can take it with you."
this show you know nothing bout web hosting
shared hosting shares a single IP address ( say 100 sites), if 1 of them sites sends out spam and the IP gets blacklisted then this will show for the IP for the 100 sites.
if you have 1 of these sites and then get a clean dedicated IP then the blacklist will no longer effect your site as you are no longer on the shared IP.
then its up to the host to locate which site had the IP blacklisted and get rid of that site and then to contact which RBL blacklisted the IP to have the IP unlisted.