This exercise has been given a bad reputation, through no fault of its own. When done incorrectly (like any exercise), you won't get results and you'll risk injury.
But that's not the biggest problem here. Just because it's been labelled as an abdominal exercise and it works the side muscles (i.e. the ones under your love handles), people expect it to work wonders.
The reality is that our bodies burn fat as a whole. There's no direct link between doing side bends and reducing love handles.
The best way to get rid of fat around your stomach and sides, is to do a combination of a full
fat burning exercises.
So if you came here looking for love handle relief, get to those pages now.
What are dumbbell side bends good for?
When done with good technique, they will strengthen your obliques. The functional aspect of this is important, because everyday activities often involve side bending and twisting.
The main thing to remember when doing this exercise, is that it's more about improving muscle tone, rather than building bulk. That means using moderate to light weights.
The quality of your movement is so much more important than the quantity of the weights. You'll build strength quicker and avoid injury with slow, controlled movements.