Common scams to avoid

[Ren]

Buyer reverse the payment

Scammer – Buyer
Scammed – Seller

Step 1 – Buyer pays for the account via paypal
Step 2 – Seller provides account info to buyer
Step 3 – Buyer changes account info
Step 4 – Buyer reverse the payment via paypal claim

Seller takes away money with no reply

Scammer – Seller
Scammed – Buyer

Step 1 – Buyer makes payment for the account via a payment gateway without charge back
Step 2 – Seller does not provide account info to buyer

Seller changes account info after transaction

Scammer – Seller
Scammed – Buyer

Step 1 – Buyer makes payment for the account via a payment gateway without charge back
Step 2 – Seller provides account info to buyer
Step 3 – Seller changes account info after transaction

[Kouris]

How you supposed to be sure the buyer will not just always reverse the payment?

Is that a common occurence here?