I have a client who wants to buy an old domain that in no way just by looking at the name of the .com indicated adult content.. But by looking at the archive's back in 2007 there was porn movies there.. The good news all the backlinks are gone from google and yahoo so would it be safe to buy this domain without having to worry?
It probably wouldn't matter because you could request reconsideration at google with the explanation that you have purchased it and are developing it into whatever it is your developing it into. I have heard them requiring further proof of this, but I am sure escrow receipts and such would suffice. In most cases, however, it seems they do not care and will let you back in the index as long as you are following their quality guidelines.
It might have to take a little time in the beginning for Google to acknowledge this one as new completely. Google does always keep site history and also looking for a keyword in domain name. If your domain has a "porn" keyword and you would make a new site about jewelry then the consistency in build up content is a must until Google acknowledge about the change.
If the price is really good, go for it. You can always salvage a domain. I have turned around banned domains and made a profit.