Here are a list of features found in an angels human disguise

Rubber Skin

No matter the quality of an angels disguise, their skin will always be rubber. Angel bodies are not tangible, so if you were to press on an angels skin, it would feel like poking a very thick balloon or air mattress. I would advise against poking it with a pin to see if it would deflate. That would be funny, however instead I think you will just make the angel very very mad and then it will eat you.

Chest Hole

Chances are you won't just come across an angel with its chest hole exposed walking down the street, but the hole is a dead giveaway that someone is an angel. The chest hole is a wrinkled hole that tunnels through the angel's chest entirely. They can range in size from a quarter-size to nearly the entire chest. The definite purpose of the chest hole is not known. If I had to guess, The hole holds a "soul" of sorts. some vital part of the angels true body that cant be covered by rubber skin. or maybe its just a style choice, who knows. DO NOT stick your hand in/through the hole. being in close proximity with an angel is dangerous enough, but sticking your hand into their center of gravity is sure to cause serious physical and psychic damage. Note also how an angels chest will have no nipples, and will not appear to rise and fall (in a manner suggesting breath) An angels chest might have ridges or pits to suggest ribs, collarbones or belly buttons.

Empty Eyes

NOTE: IF THE PUPILS ARE A + SHAPE, AVOID AT ALL COST! cross pupils indicate a seraph in a late stage of decay.
An angels eyes will be large, black and empty. The sclera will have no veins or blemishes. Angels can only move their eyes similar to a servo on an animatronic. Therefor, an angel cannot really focus their eyes on a subject, instead they merely point their eyes in a general direction. Looking into an angels eyes causes no danger- they are only aesthetic, after all. An angel will blink in a specific sequential pattern, if at all.

Hollow Mouth

Actually, the angels disguise is entirely hollow. The mouth is just the easiest way to see inside. Despite having no tongue or vocal organs, An angel can mimic convincing human speech. However as a mimic, an angel needs to 'steal' a voice. An angel's voice will have the exact same tone, pitch and accent as an existing person. The human who's voice is stolen will, as expected, no longer be able to communicate and will often die soon afterwards. After a while, if the angel is not very powerful, their voice will become thin and reedy. They will have to continue to steal voices as long as they intend to interact with humankind.

Thin Hair

An angel's hair will appear very thin and greasy. It can be any color or texture, however it is often straight. An angel will not care about hairstyle or upkeep, so the hair will often be at an awkward length or very messy. Angel hair is very soft to the touch, and despite its look will not actually feel greasy.

No Genitals

An angel will have nothing but a smooth mound where any sex organs would be present. It is very unlikely for you to ever see a naked angel, unless you knew where to look. Groups of disguised angels might gather at remote locations during the night, shedding their clothes and engaging in ritual dance or song. Be very careful though, if an angel were to ever catch you peeking you would certainly be incinerated immediately.

Silent Footsteps

An angels feet never truly touch the earth. They float a very tiny distance above the ground, unnoticable if they are wearing shoes. They hover just enough to where their feet make no sound. This is also partially due to the hollow nature of the disguise. An angel will often be barefoot or wear open-toed shoes.

Faint Glow

An angel will have a very faint light around their entire body. They dont exactly shine in the dark, but an angel's skin can look peculiarly raidant, clear and warm. Sometimes, typically dark areas like the nostrils or ear holes will be strangely well-lit. Some angel's glow is harmful to human eyes, and the angel will literally hurt to look at.

Aggravating Aura

An angel's aura is a very toxic thing. Being in close proximity to an angel can cause behavioral changes such as mild annoyance and aggression, violent thoughts, homicidal ideation, hysterical crying, screaming, laughing or singing, amnesia or a sudden total change in personality. Prolonged exposure can cause serious physical effects including internal bleeding, loss of teeth, hair, eyes and nails, cartilage dissolution, skin cancer, brain calcification, spontaneous human combustion and even sudden metaphysical warping of bone and flesh.