I use Xfce as a desktop. It's one of the few desktops that actually follows the Freedesktop.org trashcan spec [1]. Basically, trashed files are moved into ~/.local/.Trash/files, and some metadata about the file is saved into ~/.local/.Trash/info.
Gnome doesn't follow this. Instead, files are moved into ~/.Trash. Since I run various Gnome applications from within Xfce, when I delete a file from within those applications, they go into Gnome's trashcan, which Xfce's trashcan cannot see. Even better: when I view removable media using Thunar (Xfce's file manager), it's running Gnome's volume manager inside of it. So if I delete files, they go into Gnome's transhcan, not Xfce's, even though I'm using an Xfce app. Lovely! [1] http://www.freedesktop.org/wiki/Specifications_2ftrash_2dspec
