If the companies didn't want you to do this, then they wouldn't let you do this.
Why would a company want you to do that?! The only reason some allow it is that it's very difficult to have a policy that allows honest customers to return items they don't like (for whatever reasons) while at the same time preventing this behavior.
You'll find that there are many companies who have stopped the practice of accepting returns for any reason, for the very reason you stated. If you were running a product company, would you enjoy and encourage the "free rental" behavior?
Why would a company want you to do that?! The only reason some allow it is that it's very difficult to have a policy that allows honest customers to return items they don't like (for whatever reasons) while at the same time preventing this behavior.
You'll find that there are many companies who have stopped the practice of accepting returns for any reason, for the very reason you stated. If you were running a product company, would you enjoy and encourage the "free rental" behavior?