debug on different sites on multisite wp

Seconded! I’d like to enable debug mode for individual sites.

Third vote for this ??

Psst. You can!

With props to Mike, let’s say you wanted to only debug foo.example.com:

if ($_SERVER['HTTP_HOST']=='foo.example.com')
  define('WP_DEBUG', true);
else
  define('WP_DEBUG', false);

Or even shorter:

define('WP_DEBUG', $_SERVER['HTTP_HOST']=='foo.example.com');

https://wordpress.stackexchange.com/questions/6712/how-to-set-configuration-options-for-particular-sub-blogs