I just want to know if I am going to buy a PR domain, how can I know whether it is dropped or not? Is it only determined by Google's backlink? If yes, how many links are enough to qualify? Also, a dropped domain still has a PageRank, so what's the problem of them? Why people don't like them?
Not sure if I understood...but if you are asking what I think you are...try DomainTools. (Sign up for a free account to access more detailed info...but you can still use the WHOIS without signing up) Their WHOIS service will show you WHEN the domain was registered...as well as PREVIOUS registrations. IT also says how many "drops" there have been. In the detailed info, you can see what years it was reregistered, different servers and registrars etc. Also use : http://checkpagerank.net PR validity (although I've found it to have some oddities at times) It shows you how many backlinks...and exactly how long the most RECENT registration has been.