They really have to fit. Like if you are representing a rather grounded story and add squelching noises its really off-putting, however I will sometimes enjoy those shittier rpg-maker (not always shitty in the porn department) games where this stuff is common. And if I am playing an AVN that focuses on like a story and one that just feels added and doesn't sync to whats happening then its kinda gross. So to me I think it synchronizing with what I am seeing is important