hi primecollection_in1,
The point raised by you on 'a user leaving a negative feedback even without paying for the same'
as snrama pointed out, very soon, some changes in the feedback system will be rolled out, one such change, Neutralising feedback left by members who don't participate in issue resolution processes, will hopefully resolve situations such as mentioned by you.
To know more about the changes, please visit: http://www2.ebay.com/aw/in/200509221755372.html
I hope this helps!
Regards,
Sapana