You really can't, even if it was sharing the exact same ones directly from someone else's mouth, let alone ones that have been dunked in water and washed.it's about the cutlery not being clean. It's different when you are at home but when you are sharing with 10/11 other people and the cups, forks and spoons that end up in peoples mouths aren't cleaned properly you can pick up cold sores etc.
I think all these mega corps advertising their chemicals and Mrs hinch have a lot to answer for, and the knock on effects caused. But that unpopular opinion is probably best raised elsewhere
Cold sores - questions and answers - Herpes Viruses Association
Questions and answers on treating cold sores (facial herpes, herpes labialis), and how cold sores are transmitted and spread.
herpes.org.uk