If you have a separate user writable drive mounted, you may have encountered the same problem I had. If your DE cannot create
.Trash-$uid, most DEs will not delete files to the trash at all and KDE will copy deleted files to your home partition. I find both behaviors frustrating.
The solution is rather simple: look at the spec and create the trash directory manually.
Now delete some file from that partition and check that is lands to
.Trash/$uid/files. Your trash directory now works properly.