I was hoping it was going to be a styling issue but for some reason it is generating nothing. The code below is what your website is generating (right click your browser window and select View Page Source to see for yourself). Your products should appear between the <table width="auto" border="0" cellpadding="1" cellspacing="1"> and </table> tags
<div id="productListing">
<div id="productsListingTopNumber" class="navSplitPagesResult back">Displaying <strong>1</strong> to <strong>2</strong> (of <strong>2</strong> products)</div>
<div id="productsListingListingTopLinks" class="navSplitPagesLinks forward"> </div>
<br class="clearBoth" />
<div class="centerBoxWrapperContents">
<table width="auto" border="0" cellpadding="1" cellspacing="1">
</table>
</div>
<div id="productsListingBottomNumber" class="navSplitPagesResult back">Displaying <strong>1</strong> to <strong>2</strong> (of <strong>2</strong> products)</div>
<div id="productsListingListingBottomLinks" class="navSplitPagesLinks forward"> </div>
<br class="clearBoth" />
</div>
If you filter on something that genuinely doesn't exist such as this where I've just swapped the 80x32 for 32x80.....
http://www.bigandtallwarehouse.com/Jeans?sort=0&fltSizes[]=32x80
You correctly get the message 'There are no products to list in this category.'
To me, it looks like the filter is working, especially after you'd confirmed the generated SQL does return the 2 expected products. You could try looking at the file that generates the product listing table to see why it isn't generating any products inside the table. Working backwards from there should eventually lead you to the cause of the problem.
If you can work out the cause, hopefully we can find a solution.
Sorry I can't be more help!