During the mouth-inspection scene, subtle dialogue changes can provide additional clues. a successful D20 roll can also provide insight. However, the clearest giveaway is the number of cum shots: fake characters often produce only one, while real characters typically produce several. Lastly, the dialogue during the finishing scene may describe the resulting load as small or pathetic versus unusually large or massive (small meaning fake). there’s also an additional giveaway on how the character looks after the scene is over you may notice something different between the real and fakes. this will of course vary and tweak as I continue updating the game. I hope this helps!