It's not really possible to stop the browser sending the "furnishings" value, even if it's empty - other than Javascript but you can't always rely on this.
This PHP code deals with it though:
PHP Code:
if (empty($_GET['furnishing'])) {
/* if the value in the URL is empty like:
http://www.site.com/results.php?furnishing=
then do something here...
*/
}
elseif (!empty($_GET['furnishing'])) {
/* if the a value for "furnishing" passed in the URL is like:
http://www.site.com/results.php?furnishing=Fully+Furnished
then do something different
*/
}