I guess I meant that those constructions are bad grammar for standard English. Believe me, I am not one of those "English only" types. But, I have had a problem getting kids to understand that it is necessary to speak standard English in business and school situations.
The "I seen" and "he don't" are much more prevalent in other parts of the country, even among well educated speakers. If someone spoke like that here, even in a social situation, it would not be seen as something positive. Yea, we are language snobs here, so don't start yelling! When I was first married, my husband used both of those expressions, because that's what his parents used. When he was getting ready to go back to finish his BA, I explained to him that he probably shouldn't use certain language forms at the university. He just never thought about it, as it was all he had ever heard.
Actually, I find regionalisms and dialects quite interesting to learn about.