why is selling something and putting it as collateral at same time a scam ?
Because when you sell it,it no longer belongs to you or the lender who has it as collateral.How difficult it is for you to understand ?ok thanks and really I did not like the rating you left on me. If possible and you feel relevant please remove it, I dont think anyone is childish enough to trade without escrow ... or maybe fine as you wish 
The rating is well deserved.According to Lutpin that is not a trustworthy behavior and YOU can't decide whom he should trust.If you really want to prove your innocence contact other DT members and ask them to put a feedback against Lutpin's.
Apparently the OP has given up on trolling Lutpin and moved on to the next target:
https://bitcointalk.org/index.php?topic=1399840
https://bitcointalk.org/index.php?topic=1399820