I always feel the number 2 is the best preventive measure against this while the others also help except number 1 because the account was created solely for that purchase and things will become even way difficult.
Interacting with such money even if it is refund is an issue and the legal forces with other restriction like bank account getting locked is not something that will be easy to get off with in this country even with record of receipts. We have read or seen stories about this spoken off a number of times. While I don't really know an effective way to prevent this since I can think of a back door these scammers can use, I just hope not to be a victim or anyone around me.
This is very important lesson for p2p traders that they should have at the back of their mind. When trading always be careful of the kind of price that we take when we see a price that is unexpectedly high when compared to the current rate. This is a lesson I have to take and look out for not to fall into such traps and and problems later. Because unnecessarily high price is a sign of a red flag and we should look out for it to avoid problems on the long run.