Some Clarifications:

To be fair here's a more professional article showing the difference between accent and dialect: http://americanenglishdoctor.com/wordpress/literacy/english/dialect-vs-accent

And here's a brief but excellent explaination describing the delicate distinction between a stereotype and a generalization. It is important to not "throw the baby out with the bathwater": http://drewfordski.blogspot.com/2006/02/stereotypes-vs-generalizations.html

Here's another article with examples of high and low context cultures: http://www.via-web.de/high-context-vs-low-context/

This site by a famous Sociologist is an excellent resource where generalizations can be used in a respectful way for the purpose of good: http://www.geert-hofstede.com/hofstede_belgium.shtml It's not just important for Autistic people to learn unwritten rules but also for people in general to promote understanding of other cultures' perspectives.