title: Magento's getAttributeText is inconsistent
body: <p>I'm trying to write some custom logic for browsing and searching in a Magento store.</p>
  
  <p>So I figured I'd overwrite getProductCollection for both Mage_Catalog_Model_Layer and Mage_CatalogSearch_Model_Layer.</p>
  
  <p>I'm trying to make decisions based on what the value of certain Attributes are for some of the products in the collection, but I can't seem to get the text value of all attributes.</p>
  
  <p>The function as I've overwritten is:</p>
  
  <pre><code>public function getProductCollection()
  {
      if (isset($this-&gt;_productCollections[$this-&gt;getCurrentCategory()-&gt;getId()])) {
          $collection = $this-&gt;_productCollections[$this-&gt;getCurrentCategory()-&gt;getId()];
      } else {
          $collection = $this-&gt;getCurrentCategory()-&gt;getProductCollection();
          $this-&gt;prepareProductCollection($collection);
          $this-&gt;_productCollections[$this-&gt;getCurrentCategory()-&gt;getId()] = $collection;
      }
  
      //ben
      $collection-&gt;addAttributeToSelect('parent_sku');
      $collection-&gt;addAttributeToSelect('door_color');
      foreach($collection as $product) {
              echo "\nSKU: ".$product-&gt;getSku()."\n";
              $product_data = $product-&gt;getData();
              if(isset($product_data['parent_sku']) &amp;&amp; ($product_data['parent_sku'] != '')) {
                      echo "GETDATA PARENT: ".$product_data['parent_sku']."\n";
              }
              if($product-&gt;getAttributeText('parent_sku') != '') {
                      echo "ATTR TEXT PARENT: ".$product-&gt;getAttributeText('parent_sku')."\n";
              }
              if($product-&gt;getAttributeText('door_color') != '') {
                      echo "ATTR TEXT COLOR: ".$product-&gt;getAttributeText('door_color')."\n";
              }
      }
      //end ben
  
      return $collection;
  }
  </code></pre>
  
  <p>This produces output like:</p>
  
  <p>SKU: TEST_SKU_1<br>
  GETDATA PARENT: TEST_SKU_2<br>
  ATTR TEXT COLOR: Black  </p>
  
  <p>Notice:<br>
  I add both 'parent_sku' and 'door_color' as attributes to select.<br>
  I can access door_color using $product->getAttributeText()<br>
  I cannot access parent_sku using $product->getAttributeText()<br>
  I can access parent_sku through $product->getData()  </p>
  
  <p>Any time I call $product->getAttributeText('parent_sku') it returns false.</p>
  
  <p>I assumed that this was a caching problem, but I flushed the cache and that didn't seem to help.</p>
  
  <p>Does anyone have a clue why I can't access the value of 'parent_sku' through getAttributeText()?</p>