I'm having trouble picturing this. Maybe if I had a demonstration... Not watching it on YouTube, or anything, because that would be someone else's kiss, and I want to be able to answer for myself. Perhaps if we worked together on a sample kiss of the kind to which you refer, I could formulate a more complete, considered, response... Alternative definitions of "public" might also need to be explored. On the street might certainly be public, but on the street during Folsom? In the bedroom, with the cat watching? In front of my class? In the back of someone else's class?