To my way of thinking, CFD's are akin to betting on the races at a TAB.
You go in & bet on an event ... you don't have to own the horse you bet on. Same with CFD's ... ownership of the share is never an option of the "bet". It's a 3rd party transaction which should have no bearing on the actual event. Where it could have an effect would be where a party with a CDF position hedges it with a real market position. In this case, from now on, a hedge in the positive direction could be acheivedby the purchase of shares, options or calls while the negative direction could by covered with puts or ordinary shorting.
IMO naked shorting is wrong for the simple reason that it increases the notional number of shares in play in the naked shorted company without the permission of the company or its shareholders ie shares are sold that don't exist, so for the time that the shorter is not covering there are more shares 'in the market' than the company has issued. This can do nothing but distort the market in that it clearly distorts the true supply\demand dynamic
