More of a fun fact than headcanon; but I was watching Voyager and Tuvok remarked that 'Unlike in humans, the Vulcan libido increases with time.' For Spock, I think his libido actually started out at human levels. His libido of course follows the Vulcan growth rate instead of the human patterns.
I also think that Spock experiences attraction first intellectually and then physically. So if you stimulate his mind then that's what triggers his experience of attraction and then arousal at that point. Witty banter falls into these categories for Spock because it is sometimes hard to find verbal sparring partners who he feels can match him. When he does it's a special delight for him.
I'm following The Original Series' example and noting that Spock likely experiences his first Pon Farr during the five-year deep space mission aboard the USS Enterprise under Captain Kirk. Spock is secretive about it (as I believe Vulcans generally are) and his primary method to get through it is intensive meditation and seclusion.












