It will only be deleted if you delete it yourself from the web interface, or from a computer that is synced.
Copy.com/Dropbox are
syncing products, not
backup products. If you delete something, they will delete the synced copy.
Dropbox offers a 30-day history of all your files, which can be used to restore deleted files (as well as to revert to an older version of a file). If you pay for extra storage they will keep an unlimited history.
You can view those files via their website. Also, there are scripts which access the Dropbox API to do fancier things like
restore your whole Dropbox to a specific date (my fork with a shared API key).
Copy.com only allows you to restore deleted files from the desktop client, and I don't know how long you have or what the deal is.
Bottom line, though -- I wouldn't worry about it happening. As far as I am concerned, it will only happen if I am the one doing the deletion, by accident of course.
It isn't their job to protect me from every form of stupidity I can bring upon myself.
They will protect me if my computer is blown up. They will save me when I lose my computer, or can't access it
RIGHT NOW. They will even protect me from my own stupidity if I ask them within 30 days. Good enough for me.
I assume if a file got deleted from your computer, and that change was synced to Copy.com/Dropbox... then the file *should* be in your Trash. All in all, what you are doing is making sure that whatever *might* happen to your files, chances are they will be preserved in at least one place.
I doubt you will be in the position, for example, where you deleted the files from your computer, AND you synced to Dropbox, AND you didn't notice for 30 days, AND you lost that computer or cleared the Trash (never do this unless you are sure) AND you lost your flash drive backups.