The text is drawn only when DeskScapes is enabled and running one of its dreams. Changing the wallpaper via any other method would have disabled DeskScapes automatically even if you had not uninstalled it.
An easy way to check if it has been uninstalled is to look in the c:\program files\stardock\object desktop\deskscapes folder. If there are two dlls deskscape.dll and deskscapes.dll then the uninstallation was not successful. If they are not there (remembering to check program files (x86) if you use a 64 bit OS) then Deskscapes is not running and will not be drawing any text.
Additionally if you had not uninstalled the software you would expect to see the trial nag screens on reboot.
Note that the wallpaper after uninstallation may be a static snapshot of the last dream you were running in which case that image would have DeskScapes 3 trial written on it.