A. John had such bad a sense of humor,
B. John had such a bad sense of humor,
C. John has such a bad sense of humor,
D. So bad is John's sense of humor.
E. John is having such a bad sense of humor,
Explanation: The correct structure for expressing an extent is "such + a/an + adjective + singular noun". Also, the second clause is in the past tense ("appealed"), so the first clause should also be in the past tense ("had"). The correct phrase is "John had such a bad sense of humor".
