I used Fast Car below because there had been no indication of acoustic music's hitmaking potential in the '80s. I've got a few others lined up.

Generally though I'm looking for songs that were successful despite the fact that there was no aesthetic equivalent in the pop charts at the time. When you think of '80s pop music, even if this song crosses your mind amidst the Safety Dances and Like a Virgins, it's likely to be the only song that sounds the way it does.

In soe cases those songs might be the ONLY pop hits to have had that aesthetic, and in other cases they might have opened the flood gates for a new pop music. ie you could argue for Smells Like Teen Spirit, though there could easily be arguments against it.

*shrug*