[@netweb Keymaster 12 years, 8 months ago]

This is what you want for the above:

function hide_forum_counts() {
        $args['show_topic_count'] = false;
        $args['show_reply_count'] = false;
        $args['separator']        = ' '; 
        return $args;
}
add_filter('bbp_before_list_forums_parse_args', 'hide_forum_counts' );

A full example of all the bbp_list_forums arguments to use either in a custom function or a plugin https://gist.github.com/ntwb/3797945