Sun May 14, 2017 1:40 am
Good question.
When a transaction is double spent, you will not know about it. The transactions can be submitted at different times, and look completely different. Only a full node will be able to tell, when it receives both transactions, try to sort them out, but they conflict.
Usually a site like blockchain.info, which almost never misses a transaction, will have a message something along the lines of "Warning! this bitcoin address contains transactions which may be double spends. You should be extremely careful when trusting any transactions to or from this address.".
This means that they have found two conflicting transactions, and have put up an alert. Usually wallets will not do this. So be sure to check.
Usually a double spend transaction is made to scam you (For example, overwriting a payment to you for some CSGO items, for example.) A couple of telltale signs for these are:
- Low fees (The transaction that will be reversed will usually have a really low fee to make sure that the transaction never goes through)
- A deal too good to be true (The scammer will try and get you to pay him, by trying to convince you that he's helping you)
- Someone you haven't traded before randomly comes up to you
theres a snake in my boot