If you get an email from this man it is a scam!! Paypal are aware but you may not be, his emails and Paypal receipts look authentic
He will try to buy what you are advertising (usually vehicle through Auto trader) and say he is on an oil rig and so can only pay via Paypal and has to pay shipping charges with Western Union, he will then give you a fictitious shipper address and ask you to send £600 charges via Western Union.com and will send you a receipt from Paypal saying the full amount is being held for you and as soon as this money is transferred the sale will complete and the funds will appear in your account.
Paypal DO NOT hold money for you!!
BEWARE THIS IS A SCAM BASED IN INDIA