This function returns true if the logged-in character has unlocked their guild store. Otherwise, it returns false.
This function will return true if it makes sense for your character to buy seltzers from the Knob Goblin Laboratory. If you are a spellcaster or a high level Accordion Thief and have unlocked your guild store, then you should be buying Magical Mystery Juice to restore your MP. If not, then seltzers are a good idea if and only if you have the outfit that allows you to access the Laboratory store.
When not logged in, this function returns false.