Possibility of validation of transaction TX id
A txid is little-endian representation of the double sha256 of the serialized tx. Hence, if they send you a wrong or incomplete txid there is no way of validating it without the serialized tx.

Moreover, you should be careful when identifying txs just by its txid, if not careful enough (you accept 0-confirmation txs, or txs that has not gone deep enough in the blockchain), they could double spend the same utxo thas has been used to pay you.