Personalization in XperienCentral depends on a number of things:

The HTML of the page
The XML containing request and session information
The XSL used to reformat the page based on personalization expressions

These three are combined on the server side, which results in plain HTML being sent out to the visitor of the website. The XSL that is used to transform the combined page, request and session information can be viewed by adding xsldebug=true to the URL of the page:

http://<backend server name>/web/show/id=123456?xmldebug=true

In order for this to work, you need to be logged in with the Tomcat administrative login. To experiment with transformations, try the BIT-101 XPath Query Tool developed by Keith Peters.