Anyone that thinks they are free from risk is fooling themselves. Every action in this punting life carries an element of risk - especially the getting seen by someone risk!
Herpes is skin to skin contact so if the girl has sucked a cock and caught herpes she can pass it onto you via BBBJ if she has an active infection at the time.
I think the biggest risk is oral gonorrhea. The girl can pass this to you via oral if she has caught it from sucking an affected cock. If the girl has a sore throat then dont get her sucking your cock at all. Check out the link below but this infection is different to an infection of the genitals.
https://www.verywellhealth.com/oral-gonorrhea-5219590
You need to make your own mind up on risk. Its not for us to say whats risky or not but the more uncapped cocks the girl deals with the higher the probability that you come across an issue.