1) No instinctive understanding of unwritten social ‘rules’. We don’t know all the little do’s and don’ts that NTs seem to be born knowing, or learn before they leave kindergarten. So all too frequently, we inadvertently blunder right through those rules.
2) No instinctive ability to read other people’s body language. This adds to 1), as we don’t see the non-verbal signals that tell us we’ve dropped a clanger. So we go on blithely unaware, until bang - a whole bunch of stuff comes crashing down on our bewildered heads.
3) No ‘hidden agenda’. Often some of the things we say, if said by an NT, would have all sorts of complex, implied layers of judgement and criticism. So NTs assume we mean them too - when in fact, if we say, for instance, that someone is fat, unemployed or has a big nose, we usually mean they are fat, unemployed or have a big nose. End of.
4) Terminal honesty and straightforwardness. This is intertwined with 1), 2), and 3). We’re very honest, with a tendency to speak first, and think later! Honesty is a good quality overall, but it can be interpreted as deliberate rudeness by NTs who don’t understand.
5) Little ability to do small talk. We don’t pick up all the unspoken messages being exchanged through this (I was in my 50s before I even realised these messages existed), and so it seems pointless, frustrating and deeply boring to us. But if we don’t do it, we can come across as surly or disinterested in other people.
6) Don’t like eye contact. If we’re not looking at people when we speak or listen to them, this can also be interpreted by NTs that we’re not interested in them or what they’re saying. NOTE: Pretending to be interested, even if you’re not, is considered polite social behaviour by NTs.
7) Auditory processing difficulties. These tend to make us come across as ‘slow’ or disinterested, when in fact we are simply struggling to hear/interpret what’s being said, especially in large group situations, eg staffroom morning tea sessions. But avoiding them without explanation often appears to others like we don’t like/are snubbing them.
8) Prosopagnosia, or face-blindness. If we don’t recognise someone, and hence don’t speak to them, or walk right by them, this can also come across as snubbing or rudeness.
9) Alexithymia. Difficulties with recognising, managing and expressing our emotions means our emotional reactions can come across as ‘inappropriate’, in when, where and how the emotion is expressed. Again, this can be seen as rude by others.
10) Difficulty moderating our voice tone or volume. Some aspies/auties talk very loudly, and this can be interpreted as ‘rude’ too, in the sense it doesn’t consider other’s needs. Also, if we habitually talk in a monotone, this tends to be interpreted as us being ‘blatantly’ bored or disinterested, and hence rude, by NT rules.
I want to emphasise here that though most of these factors are intrinsically bound up with our autism, that doesn’t mean we can’t learn to overcome at least some of them, to some degree, and/or learn ways to avoid being misunderstood. What we learn, and how much, and how well we’re able to put it into practise, will of course differ from one autie to another, one situation to another. It may be for instance that we never master eye contact (though we may be able to approximate it, and fool people into thinking we’re looking them in the eye), but we can learn how to temper our honesty with more ‘polite’ phrasing or words, or to moderate our voice volume and tone. Or we might be able to master at least a little ‘small talk’, but we’re stuck with the face-blindness. (And of course some of these factors I don’t consider need changing at all, such as our lack of those hidden agendas.)
Of course, none of the above is an excuse for any autistic to be deliberately rude either. If we have learnt at least some social rules (for instance not to say certain things to a boss, teacher or other authority figure) we are as obligated to follow those rules, and as liable to criticism for failing them, as any NT would be in the same situation. Being autistic is not a carte blanche for us to say and do whatever we want, whenever we want, to whomever we want, however we want.
There are probably other factors that I haven’t thought of, and it’s likely that many of them we can’t (or shouldn’t) do much about, but at least if we know the most likely reasons why we’re being called ‘rude’, then we have some chance of either a) finding a way to explain ourselves, b) finding ways to improve our ‘social performance’, or at least c) not being so totally overwhelmed and upset by the accusations of others, that we end up dumping on ourself for being ‘bad’ in some way. We are what we are, and while we’re not exempt from social obligations, we do also have the right to simply be ourselves.