// WP_Query arguments
$args = array (
    'post_type'              => 'publicidad',
    'post_status' => 'publish',
    'post_type' => array('publicidad'),
    'category__in' => $wp_query->get('cat'),
    'tax_query' => array(
        array('taxonomy' => 'ubicaciones','field' => 'slug','terms' => 'ub-categoria'),
    'orderby' => 'rand'
);

// The Query
$query_ads = new WP_Query($args_ads);