If a site has had mailware but removed, is it good SEO to make links from that site to ones own? And also, a domain name that has PR but no site, is it good for SEO to have some links there to other sites? REALLY NEED CLEAR ANSWERS, THANKS.
Well, your question is just too much confusing in the second half I really can't understand "A domain name that has PR but no site" How can you get back link from the domain which has no site??? :O , Rest the first part malware is concerned I don't think having a back link from that site is going to benefit you, look its like I have website which was having a bad reputation i.e malware and some sort of things, and if after a while if I take down those ..... blah..blah... but still that site needs much more care to get its reputation back, what google do with these sites is they black listed them and getting a back link from it is surely going to act as a poison link. So, I'd say better not to get back link from such places rather than start working from the scratch
It really depends on what the site has done to its reputation. If they removed the malware and they are still blacklisted by google its best not to get associated with them. Bad neighbor links will derank your keywords.Why take the risk? There are sites that can check if a site has been blacklisted or not but i am not sure how accurate that is. For the second question:How can you link to a domain name without a site? Good luck