I dont think there is any specific look, sounds like some very ignorant people.. However there are forms of body language that many on the spectrum have that may come across as intimidating... One is obviously the resting face look, for some it may come across to others as stay clear of me when infact its not the case.. The other is the stare, ie when you are just looking at someone for intrigue, prolonged visual staring can make people feel uncomfortable or the people around you will alos presume you have an attraction to them when in reality you are momentarily intrigued by their look, hair or clothing style... Also the conversation stare, i have somewhat stopped doing this now as it was pointed out to me, but sometimes when i was in a one on one conversation with someone i would hold eye contact indefinitely and they would suddenly ask why i kept looking into their eye, this always baffled me somewhat as i would respond by that im just concentrating on what you are saying, but apparently this makes people feel uncomfortable, so i tend to consciously look away from time to time, its a little ironic as i dont really like looking directly into people eyes and will often focus on the mouth when talking to someone.