Re: SELECT from mytbl;

Or even, slightly shorter:

EXECUTE
 'SELECT '
 || array_to_string(ARRAY(
   SELECT a.attname
     FROM pg_class c, pg_namespace n, pg_attribute a
    WHERE n.oid = c.relnamespace
      AND a.attrelid = c.oid
      AND a.attnum >= 1
      AND n.nspname = 'myschema'
      AND c.relname = 'mytbl'
      AND a.attname <> 'bad_field'
    ORDER by a.attnum), ', ')
  || ' FROM myschema.mytbl';

/E