[quote=@Kuroneko]

[u][b]Current Question:[/b][/u]
Will A Houri Necromancer who becomes a Lich experience the decomposition disadvantage that Lich or other races experience?
[/quote]
In the way that abilities are traditionally applied in Dungeons and Dragons, they are determined by a loose hierarchy. For example, you start with ability scores, then add any racial adjustments and templates, then any class adjustments. Certain root changes, such as the creature's type going from "Humanoid (Houri)" into "Undead", are going to usually have assigned consequences mechanically. Lore wise this is not always reflected. Yes, a lich [i]could[/i] be "pristine" rather than dry, skeletal and decomposing in appearance, but that is not so much how Dungeons and Dragons understands the lich or how the mechanical qualities apply.

My source comes from the 3.5e SRD, which is the "core" rules document that was put out a time ago by Wizards of the Coast. It has this to say about the lich template.

[quote=d20 SRD][i]"A lich is a gaunt and skeletal humanoid with withered flesh stretched tight across horribly visible bones. Its eyes have long ago been lost to decay, but bright pinpoints of crimson light burn on in the empty sockets."[/i][/quote]
No less, it has a source of Natural Armor and Damage Reduction (specifically magic and bludgeoning, adding to the magical skeletal concept), further suggesting the story component they attempted to reflect.

If you are trying to avoid the more overt touch of the grave, you are better off with the Necropolitan template or Tomb-Tainted Soul feat, as below.

[quote=Realmshelps][i]"A necropolitan's skin is dry, withered, and powdery. Its eyes are as pale as driven snow, and as lifeless. It continues to dress in the fashion it preferred while living. Necropolitans are considered citizens of the little-known city of Nocturnus, but if their nature is revealed elsewhere, they are feared and hunted like common monsters."[/i][/quote]
[quote=D&D Tools][i]"Your soul is tainted by the foul touch of undeath."[/i][/quote]