Wordpress - display posts with same taxonomy term

Totally untested and I'm not 100% sure I understand your question, but this should (in theory) get 5 posts that share any of the same venues as the current post. I would probably suggest adding some Transients to this so that you aren't constantly running queries.

If it doesn't work, I suspect the syntax of my tax query is a little off. It always gets me because it is an array of arrays.

//get the post's venues
$custom_terms = get_terms('venues');

if( $custom_terms ){

    // going to hold our tax_query params
    $tax_query = array();

    // add the relation parameter (not sure if it causes trouble if only 1 term so what the heck)
    if( count( $custom_terms > 1 ) )
        $tax_query['relation'] = 'OR' ;

    // loop through venues and build a tax query
    foreach( $custom_terms as $custom_term ) {

        $tax_query[] = array(
            'taxonomy' => 'venues',
            'field' => 'slug',
            'terms' => $custom_term->slug,
        );

    }

    // put all the WP_Query args together
    $args = array( 'post_type' => 'listings',
                    'posts_per_page' => 5,
                    'tax_query' => $tax_query );

    // finally run the query
    $loop = new WP_Query($args);

    if( $loop->have_posts() ) {

        while( $loop->have_posts() ) : $loop->the_post(); ?>

        <div class="listing-title"><?php the_title(); ?></div>     
        <?php endwhile;
    }

    wp_reset_query();

}?>