One of the highest compliments a neurotypical (non-autistic) person thinks they can give an autistic person, is “You don’t look autistic.”
For the autistic person, being autistic is not a problem. The problem is navigating through a world that is not designed for their use and comfort.
To “not look autistic” takes a lot of concentration and energy.
Things that come naturally to non-autistic people, like eye contact and modulation of vocal tones, have to be practiced and rehearsed.
While the neurotypical person is discussing news, sports or the latest, “American Idol” results, the autistic person is listening for a break in the conversation that signals their turn to talk, determining if they are standing close enough, but not too close, deciding if what they have to say is appropriate, trying to figure out who is wearing the cologne that is choking them and looking for a physical escape route or quiet corner to which they can retreat in the event of a meltdown.
Trying to do all of that while filtering out other conversations, the pain of shoes that are too tight and an excruciating itch in a spot that cannot be scratched in public, can be completely exhausting.
The autistic brain is resourceful and can manage this for short periods of time, but sooner or later, it needs a break.
The person will have to pull away to a quiet space to calm and center themselves, and prevent a meltdown brought on by too much external stimulation.
If they are not able to pull away, they may have a public meltdown, say or do something socially inappropriate or sit silently in an attempt to process all the incoming information.
Those autistics who are gifted at “not looking autistic” usually plan ahead and know what places and events to avoid or have a “prop” such as a cell phone or a pet with them that they can give their attention to without appearing rude.
Even practiced, neurotypical impersonators can have slips and make social mistakes. This is where a good sense of humor can come in handy.
Telling a person that they “don’t look autistic” is usually meant as an expression of praise and admiration. Most autistics know and accept this, even though it is, in reality, offensive.
Perhaps a better question would be: “What does ‘autistic’ look like?”