How could she know?

[ChipTrippyFox]

May I speculate that he may only be asking how she thinks she could "know" if he had recently been sucked off.

"How could she know" (which is how it's worded)

Vs

"How did she know"

 

[MrCookiE]

The crack head that you payed, her/his chipped teeth left marks on your dick.