Ghosts in Vampire are like the Storyteller want them to be. Wraith: the Oblivion is not needed for playing Vampire, even if you play Giovanni characters. Vampire don't tell you anything special about Ghost perception, except that they put them Auspex 1-2 so they have sharpened senses, can see auras and a few obfuscated vampires.
But if you do use W:tO as a source, much more information is provided (obviously). The following is a description of how ghosts are in that game.
- Wraiths have sharpened senses: they can perceive the world much more clearly than the quick (people who live in the material world).
- They also have death vision: they can see the corruption, the disease and the weakness in all the material beings. They can tell if a human has a disease that is killing him, or they can spot the weak point of a structure.
- They have even life vision: they can see auras of the quick, know their feelings, or search in a multitude who has a specific feeling.
In some official crossover rules (White Wolf published many contradictory ones) these visions combined made the Wraith invulnerable to the regular uses of Obfuscate (levels 1-5).
Note that Spectres (pure evil ghosts) are very different in the perceptions:
- They don't have sharpened senses, but the contrary. Most Spectres are nearly blind and deaf to the material world. Some powers allow them some limited perception.
- What Spectres see clearly of the material world is the Oblivion sources. Oblivion sources are normally people who are evil, desperate or diseased, that is Death is strong in them in some sense or other. Of course, Vampires reunite all these qualities, so they are like a beacon to Spectres. The less Humanity has the Vampire, more will clearly he will be seen, and more will attract Spectres. I don't know how this work with Obfuscate, though.