The ASP.NET trace information can be very useful, however there are cases when you don’t want (or can’t – partial rendering) have the trace information rendered on the page. However, all is not lost, you can redirect the information to VS’ output window by changing (or adding) the web.config trace element with writeToDiagnosticsTrace, e.g…
<trace writeToDiagnosticsTrace="true" enabled="true" pageOutput="false" requestLimit="20" />