Some corrections: Its perfectly fine to use potions on those who the scroll shows will visit the vampire, unless the Vampire specifically says "don't feed potions to vampire hunters".
Similarly, the Kraken also appears on the scroll as part of its questline, and there's no specific potion exclusions for him.
Also, I don't believe the mimic appears on the scroll, and a more accurate description of its rule would be "Only give the mimic treasure map to those who would already be getting the Dizzy potion." Giving a Dizzy potion just to give the mimic map is invalid.