I just purchased a domain name but i fear it may have been blacklisted by google in the past. How does google treat old expired domains? If nothing shows up under site:domainname does that mean its NTO sup indexed? What happens with existing backlinks that exist for that domain already. Google wont penalize you for them right? Will they benefit any?
Just search for the domain name with quotes around it. If it shows up it's still in the index. If it doesn't it has been deindexed. However, if the site hasn't had any links to it in the past it might not be in the index simply for that reason.
I would say contact them and explain. But you can also wait untill the boits comes y and they see it is another site
Domains that have expired will drop from the index if no content is associated with them when google visits them. So if you find that the site has been deindexed, this may not necessarily mean it has been blacklisted, it could just mean no content was around last time it checked. As for old links that used to point to the old website, how google treats them is up for debate.