docs : comments about Infinite Scroll with filtering or sorting

_posts/docs/2010-12-10-adding-items.mdown

@@ -39,7 +39,8 @@ $('#container').isotope({ 'insert', $newItems });
 
 ## appended method
 
-The [`appended` method](methods.html#appended) is a convenience method triggers `addItems` on new content, then lays out _only the new content_ at the end of the layout. This method is useful if you know you only want to add new content to the end, and not have it processed with filtering or sorting.  `appended` is the best method to use with Infinite Scroll.
+The [`appended` method](methods.html#appended) is a convenience method triggers `addItems` on new content, then lays out _only the new content_ at the end of the layout. This method is useful if you know you only want to add new content to the end, and **not** use filtering or sorting.  `appended` is the best method to use with Infinite Scroll.
 
 [**See Demo: Infinite Scroll**](../demos/infinite-scroll.html).
 
+See also [Infinite Scroll with filtering or sorting](troubleshooting.html#infinite_scroll_with_filtering_or_sorting)

_posts/docs/2010-12-11-troubleshooting.mdown

@@ -11,6 +11,7 @@ toc:
   - { title: Images, anchor: images }
   - { title: @font-face fonts, anchor: fontface_fonts }
   - { title: CSS transforms in Opera, anchor: css_transforms_in_opera }
+  - { title: Infinite Scroll with filtering or sorting, anchor: infinite_scroll_with_filtering_or_sorting}
 
 ---
 
@@ -106,3 +107,9 @@ animationEngine : $.browser.opera ? 'jquery' : 'best-available',
 
 Also note that the [recommended transition CSS](animating.html#css_transitions) is missing declarations for Opera.
 
+## Infinite Scroll with filtering or sorting
+
+I recommend against using Infinite Scroll with filtering or sorting. This combination produces a unnecessarily complex user interaction that will frustrate your users. New content gets added, but part of it might be hidden. There is no way for the user to tell what gets hidden or re-arranged when Infinite Scroll adds more content. Exercise [moderation](introduction.html#moderation) with your Isotope implementation.
+
+If you do plan on implementing Infinite Scroll with filtering or sorting (which is a _bad idea_), use the `insert` method instead of `appended`.  
+