It doesn't seem to mention how you know, when someone claims to send you X BUCC, how much BUCC you actually received?
In case they sent you tokens using the dapp (the private way), there are "Decrypt" and "Partial Decrypt" functions in the dapp (note this will issue a transaction) under Tortuga which reveal your balance.
Running Decrypt will deanonymize any private balance you have (so only run it if you don’t remember/know what balance you have).
Partial Decrypt will deanonymize any smaller balance you input that is smaller than your total private balance.
Otherwise they can still send you tokens the usual (non-private) way via wallet (e.g. Metamask), then you would see that balance normally.