No Skill Check (everyone): If someone is taller or shorter than you by 10cm or more, and their eye color only if they have modified eyes.
Low Skill Check: If someone is taller or shorter than you by 3cm or more, if someone is heavier or lighter set by 10kg or more, whether they are older or younger if 5 years or more, and their eye color.
Medium Skill Check: Shows a character's exact height, if someone is heavier or lighter set by 3kg or more, whether they are older or younger, their eye color, ethnic background, and vaguely whether they appear to be altering their appearance in any way (wig, contact, appear). Signs if they are on any drugs or other boosts.
High Skill Check: Shows a character's exact height, weight, and age, eye color and ethnic background, and what parts of their appearance they are attempting to obfuscate (height, weight, condition, contacts, wigs). Characters with certain skill groups will show vague signs of their abilities (they have the nimble hands of a doctor, they have the rough countenance of someone used to heavy machine work, they show the telltale scars of a swordfighter).
Maximum Skill Check: Shows a character's exact height, weight, and age, eye color and ethnic background, what parts of their appearance they have modified and what their original appearance was. Which drugs they appear to be using, and whether they show indications of having specifics nanogenics. All character skills over a certain level of proficiency will show indications, along with indications whether they have used a particular skill action (combat, mechanical, medicine, chemistry, explosives, artistry) within the last hour.