On further check with automated domain appraisal sites, got some more info.
They check with various factors for the given domain names.
1. Popularity in Social sites.
2. Domain keyword worth.
3. Domain Blocked by few Anti virus companies like Norton
4. Approximate daily Revenue from sites.
5. Approx unique visitors to the site.
6. Trademark verification for the domain
7. Spamhaus block check
etc...
I hope most of the above information is required for anyone to decide their worth. Aren't they ?