Stop loss hunting is a kind of tactic applicable from market makers brokers, because they are the opposite side of your trades. They are doing this, because your profit is their loss and in opposite. In some particular moments, they may wide the spread (bid or ask or both), when orders with solid loss are near the market price in order to trigger them and to take the traders money.
They count also on this, that if you take 10 brokers, they might show on the same FX pair different prices due to different data feed suppliers, or trading spots from where they are getting feed and executions, but the difference are not too big. I mean they could move the price or wide the spread 1 or 2 pips if the price is close enough, but also not to attract your attention :).
Technically placed S/L and T/P are visible from all brokers in the MT4 Manager terminals and the dealers on dealing desks can see all of them, including pending orders.
Of course, there are a way (by using an EA to show unreal levels to your broker or to hide the S/L and T/P levels).