Let's be honest. Genuine orgasms aren't always sexy in the traditional sense of the word. People in the throes of ecstasy contort their faces into strange shapes, make awkward sounds, and pant loudly like dogs in heat. This is not always cute.
If her expressions and sighs seem measured and harmonized, rather than breathless and random, she's probably just rolling out the show she knows you want to see. If the sounds you hear suddenly make you wonder whether you accidentally forgot to close the streaming HD edition of Cocks and Dolls on your laptop, then you might want to question if she's coming from a genuine place.