I think that many of our autistic behaviors, when done by NTs, are negative. For example, i grew up in a plain Mennonite family and one of my aspie traits was that i was always fussing with my hair and clothes. I was accused of being "vain" and much too concerned about my looks. I was very insecure to begin with and this accusation made it worse. But if an NT fusses incessantly over hair and clothes, it is seen as being high-maintenance.
If an NT is always late or disorganized, it is taken as a sign that they don't care or are lazy. When an aspie has executive function issues, it looks like laziness but we can actually be working very hard to keep our heads above water.
I could go on but i think you get the picture. Over the years many of my aspie behaviors have been attributed to totally different motives than what i actually had. I see that there are aspies who can lie, but I can't lie or manipulate if my life depended on it. I could try but my face would give it away. I have questioned my own motives many times because other ppl questioned them. I am slowly learning to take myself as i am. Combine this questioning of motives from others with an aspie tendency to overanalyze and you have an aspie with serious confidence issues (me).
I still do have problems being confident but it helps to remember that I don't have to doubt myself. Sometimes need to make sure i am doing the right thing but don't need to question myself all the time.