While investigating some weird behavior on my Mac I figured out that files I deleted from the Finder (say with Cmd-Delete) were going not to ~/.Trash where they should but to ~/Library/CloudStorage/Dropbox/.Trash. The files being deleted here are not from my Dropbox; they can apparently be from anywhere and end up in this folder. Then when I look at Trash folder in the finder I see little cloud icons next to the names of the files, likes this:

What's going on here? Why is Dropbox seemingly attempting to upload everything I delete to the cloud?