Is it right to make account deletion difficult?

You know the deal. You sign up to a site, receive a couple of emails and realise you no longer want to receive the drivel that hits your inbox. So you try and delete your account.

However when you try to do this the option isn't available or they make it so difficult it makes your blood boil! Is it right to do this?

Obviously you could argue that there is a business case but I personally think it leaves the user with a bad impression and they may never return.