If your "sale!" text is too big and the badge over the products image is messing it up, please add following style in Theme Options > General > Display > Custom css box


span.onsale:after {left:-9999em;}
span.onsale {     
width: 80px;
     border-radius: 75px;
     -webkit-border-radius: 75px;
     height: 52px;
     padding: 28px 0 0 0;


Note: You can modify the above given values to fit your site

reference image: badge