I've had a look at winapp.ini since I noticed that some entries never find anything to delete or don't even show up, although I have that application installed. I'm using a German Windows XP.
In winapp.ini there are many detection and removal paths defined like "%userprofile%\Application Data\..." or "%userprofile%\Local Settings\...". This however does not work for localized verisons of Windows where these paths can have different names. The German version for example uses "Anwendungsdaten" instead of "Application Data" and "Lokale Einstellungen" instead of "Local Settings".