tedster - 5:09 am on Dec 15, 2012 (gmt 0)
I can appreciate that some UI elements are great for visitors but not for rankings. A classic example comes from some AJAX implementations for interacting... although I can usually find a way to make them SEO friendly, the naive AJAX programmer often does not code that way by tendency.
One of the earliest areas on the web where user-oriented elements on a page could be terrible for ranking was using images of text to make things look god, rather than using straight text. Come to think of that, even with advanced OCR that is available today, that can still be problematic!