so... dennis and charlie were never actually meant to make out, right?
to me, dee's description sounds way more like a closed-mouth kiss that they both Want to deepen but don't. dennis' line being "plant one on me" also implies the same. the stage directions are short and nondescriptive, with "again" suggesting that there's no notable physical change in the way they do it, and i think dee is meant to be commenting on the acting behind it rather than the fact that they actually went far enough for her liking. i also don't think meg would write a script where they were expected to make out, either.
the spitting and disgust is completely absent from stage directions, and the whole conversation about dennis eating cheese before their kiss seems to have been improvised (which makes sense, given charlie's leading question about what dennis ate and glenn's multiple aborted responses as he tries to come up with dennis' motivation for doing so lol)
all of this to say, i think charlie and glenn made this change for them to suck face on the day of