So how would one increase Appearance beyond 5 and why would humans not be allowed to have the same scale as Vampires?

@FluxIX I think this is already addressed: A vampire can afford to have an excessive and what would otherwise be unhealthy interest in fashion that far exceeds the standard human's. It might be as simple and subtle as hemming his pants by 1/8" to turn Appearance 5 to 6, but it takes an immortal clotheshorse to know that!

@FluxIX Those are, I think, separate questions from this one, and probably merit being asked on their own. The short version of each, as HICC says above, is that scores above 5 are available through dint of advanced age and magical blood, and that's just one of the game's premises. The notion that vampires can be inhumanly attractive goes along with saying they can be inhumanly smart or persuasive.

@Jadasc Intelligence, Manipulation, and Charisma (as defined in the book) are all things which can be practiced though to improve. Practicing Appearance is at the very least far more challenging and less frequent.

The characters I have in-game currently are all of Methuselah generations, so the super-human levels are of particular interest to me. Simply spending XP to increase the stat is also impossible as I do not award XP (preferring to instead have in-game actions replace traditional stat increases). When looking at the Elder characters from earlier supplements, certain clans (like Toreador, Ventrue, and sometime Setites) seem to have maxed-out Appearance stats although I have no idea as to what was done to reach those levels.

@FluxIX The NPCs depicted in supplemental materials are not constructed using the character creation rules followed with the application of XP; they're built to spec for the author's needs. It's enough to say that through dint of supernatural power, they have made themselves as powerful as they need to be. Likewise, if your PCs are of Methuselah level, it's fair to say the system is ill equipped to handle their level of improvement. At that stage, you can simply say that, as effective gods of blood and death, they use their inhuman will and power to make others see them as they would be seen.

I am downvoting this answer as it fails to address a key qualifier to the question - permanence. All the things mentioned in this answer are great situational bonuses to appearance, but are not permanent changes to the character.

@Jadasc I don't feel that hand-waving the question because of their generation is a valid solution. I agree the supplements were written to serve a goal instead of game mechanics, but I still wonder what modicum of justification was used when setting the Appearance scores that high.

@Tritium21 The OP has said they do not use XP to determine whether or not a character's stats can rise, but base it on "in game action." Given that, and following on the premise that habits are built on repeat action, I suggested some things a character might do to show that they were devoting effort to raise their mastery over their Appearance. (That was before I understood that these were 5th–6th generation vampires, about whom very little can be said definitively.)

@FluxIX That's a valid stance, I suppose, but beyond the scope of this question. If you'd like an answer to "Why are Elder Vampires' attributes so high, and how did they achieve those levels of skill?" that's something you should ask under its own cover.

The things you mentioned are still not permanent - they are situational.

@Tritium21 Yes. In the absence of XP, the only way to demonstrate the effort to improve something permanently is to repeatedly undertake situational activity until the results become permanent. Each time you pick up and put down a weight, that's a situational act; it's doing so repeatedly that raises Strength. That is the premise of my answer.

But in the white wolf systems, that's the justification for spending XP, not something to do in spite of spending XP - specifically responding to your example in comments. None of the things you list in your answer should ever change the stats on the sheet, and should only reduce the threshold of success.

I agree with everything here, but it also seems incomplete. Unfortunately, it may be incomplete because the source material itself fails to provide a satisfactory basis for a more complete answer.

@TimothyAWiseman I'm down for improving it in some way if you can think of one.