Stars in the product list should only be displayed if there is at least one rating.
that was my solution in Product.php But this doesn't work:
<?php if ($this->allow_review){?>
<?php if (strlen($curr->review_plus) > 1) { ?>
<div class="review_mark">
<?php print showMarkStar($product->average_rating);?>
</div>
<?php }?>
<?php }?>