How will i know if the receipt I'am auditing is genuine?

Invoice/receipts has letter head of the vendor (address, tel no, and even the bank details), no erasures, with reference no,

Based on number of forensic and analytical information. where, it should be signed by the receiver rather than a copy, have a reference number, with a description of the amount and the reason of the receipt and against which invoice. further the receipt amount should not exceed the invoice amount. 

Based upon conforming results of the sampling inspection at receipt stage with reference to design requirement or drawing.