Best I can tell guests also sometimes randomly drop a percent to fuck with you. I've just reloaded a save a few times trying to get Sofia to 90%, all three cards and the item, level 5 character, characters in the housekeeping/mechanics/clinic/security to keep those at 100%, and she still gets 89% satisfaction.
It's also funny that the game incentivizes prioritizing "VIP" guests after non-VIP guests, since getting a strike on them doesn't matter. Maybe a later version could add a 25% reward bonus to VIP guests that have no strikes or something.
The % drops you'll see are probably because the staff member doesn't have full skill XP.
Say Hana is level 5 for Club singing skill, max 750/750, that will give her 60%.
If Catalina is level 5 Club skill, but only 650/750, she will get lower %, say 58-59%, e.g.
The very best you can do for Sofia at VIP 5, without the Office, is 85%.
That's with full level 5 skill (750/750), 60% + Room Upgrade Item, 65% + Equippable Item (from Attic), 70% + 2 x job specific +5% cards, 80% + The Courtesan card for extra 5%, maximum total of 85%.
She needs 90% for VIP 5.
You cannot make it without the extra 10% from the Office, which takes it to 95%.
Or 90% if you don't bother with The Courtesan.
The prioritisation is because non-VIP guests need to have their correct choices provided by the player.
Once you VIP a guest at their respective level, the options are automatically correctly chosen the next time they arrive.
So, for non VIP guests you can fail the choice of option & also fail the service level, whereas for a VIP guest you can only fail the service level aspect.
Given this, the prioritisation is pretty logical & obvious: One guest has something for you to choose & requires your interaction, the other does not.
Guess which one takes priority? lol
I get what you mean, that VIP you'd expect to receive the best service.
Think of it more as frequent flyer loyalty bonus type.
Because you've stayed there with complete success before, they know what you like now, so can serve you adequately, more easily, with less involvement from you.