Are these useful criteria for judging, advising on, and teaching grammatical acceptability?
Grammatical acceptability
In this book the following criteria* are adopted for grammatical acceptability in British English to determine whether or not an item or structure is included. ‘Widespread’ here means across speakers of both genders and across a wide range of ages and social and regional backgrounds.
• Included: in widespread use in both the written and spoken corpus (most forms are in
this category).
• Included: in widespread use in both the written and spoken corpus but not approved in more prescriptive grammar books and often avoided by many writers of formal English, for example, split infinitives, stranded prepositions (e.g. That’s the woman I gave it to, compared with That’s the woman to whom I gave it).
• Included: rare or not occurring in the written corpus but widespread and normal in the spoken corpus (or example, ...Headers and ... Tails), and vice versa.
• Not included: regionally or socially marked in the written and/or spoken corpus but
widespread and normal within major regional/social varieties of British English
(for example, the use of ain’t).
• Not included: non-occurring and unacceptable in all varieties of British English
(for example a structure such as he did must speak).
http://www.cambridge.org/elt/cge/cge/pdfs/Introduction_to_Grammar.pdf
Grammatical acceptability
In this book the following criteria* are adopted for grammatical acceptability in British English to determine whether or not an item or structure is included. ‘Widespread’ here means across speakers of both genders and across a wide range of ages and social and regional backgrounds.
• Included: in widespread use in both the written and spoken corpus (most forms are in
this category).
• Included: in widespread use in both the written and spoken corpus but not approved in more prescriptive grammar books and often avoided by many writers of formal English, for example, split infinitives, stranded prepositions (e.g. That’s the woman I gave it to, compared with That’s the woman to whom I gave it).
• Included: rare or not occurring in the written corpus but widespread and normal in the spoken corpus (or example, ...Headers and ... Tails), and vice versa.
• Not included: regionally or socially marked in the written and/or spoken corpus but
widespread and normal within major regional/social varieties of British English
(for example, the use of ain’t).
• Not included: non-occurring and unacceptable in all varieties of British English
(for example a structure such as he did must speak).
http://www.cambridge.org/elt/cge/cge/pdfs/Introduction_to_Grammar.pdf