Spitting in someone's mouth or having someone spit in your mouth can potentially increase the risk of transmitting oral herpes (HSV-1) if one person is infected. Herpes viruses are mainly spread through direct skin-to-skin contact, so saliva exchange increases this close contact and potential for transmission.

It is essential to be aware that even without visible symptoms, a person with herpes can still transmit the virus. If you are concerned about possible exposure or have any symptoms like cold sores around the lips or inside the mouth, it would be wise to consult a healthcare professional for guidance on testing and precautions.

Practicing safe hygiene measures such as avoiding sharing utensils, drinks, lip balm/glosses during outbreaks when active lesions may pose higher risks could help reduce chances of spreading HSV-1 orally. Stay informed and seek medical advice whenever needed!