The way I look at it is it is another catalyst that changes the environment just like wind, current, cloud cover, etc. It can have both positive and negative effects but ultimately it does change the environment. The trick is to understand when to use it and which situations it is optimal.
To clarify, the negative effect is it may draw the bait away from the bottom closer to the boat which will make the fish suspend. On the positive to this, the fish will typically be active and be feeding.