Filter by category just for unlogged users

I am building a plugin that uses a ‘Confidential’ category for the exchange of internal infos between logged users. Unlogged users are not supposed to see that the confidential posts exists. Conversely, logged users can access to confidential posts from the dashboard.
Now, I have managed to prevent confidential posts from displaying.
Here are the filtering functions:


// Filter posts in the Confidential category
function dbmod_filter_cp_join($join) {
global $wpdb;
if (strstr($join,"JOIN $wpdb->post2cat ON (is_posts.ID = is_post2cat.post_id)")) {
return ($join);
} else {
return ($join." LEFT JOIN $wpdb->post2cat ON (is_posts.ID = is_post2cat.post_id)");
}
}
function dbmod_filter_cp_where($where) {
global $confidential_cat, $wpdb;
return ($where." AND $wpdb->post2cat.category_id !='"."$confidential_cat"."'");
}
/// Excludes confidential category from category lists
function dbmod_exclude_cc_from_list($content, $category = null) {
global $confidential_cat;
if ($category->cat_ID == "$confidential_cat") {
return ('');

} else if ($category == null) {
return $content;
}
else {
return $content;
}
}
///
// HOOKING IN
add_filter('posts_where', 'dbmod_filter_cp_where');
add_filter('posts_join','dbmod_filter_cp_join');
add_filter('list_cats', 'dbmod_exclude_cc_from_list', 10, 2);
?>

There is a problem with these functions. Logged-in users can see the post titles (in my tweaked dashboard) but they can’t see the pages. The filter prevents the post from displaying.
I should add an if statement that disable the filtering if
1) The user is logged-in
AND
2) the confidential post is being loaded IN A SINGLE PAGE
How do I detect these points?
Any suggestion is welcome.
Davide