Use of Time wrote:
Sure but the original question stands. Off all the races Vulcans have encountered, humans seem to be able to push the right buttons to get an emotional response.
Judith and Garfield Reeves-Stevens's superb Soval-Forrest scene in "The Forge" may shed some light on that:
SOVAL: We don't know what to do about humans. Of all the species we've made contact with, yours is the only one we can't define. You have the arrogance of Andorians, the stubborn pride of Tellarites. One moment, you're as driven by your emotions as Klingons, and the next, you confound us by suddenly embracing logic.
FORREST: I'm sure those qualities are found in every species.
SOVAL: Not in such confusing abundance.
FORREST: Ambassador. Are Vulcans afraid of humans? Why?
SOVAL: Because there is one species you remind us of.