Watch the Sweeping Sauce online guitar lesson by Jennifer Batten from Rock Sauce For Lead Guitar
Each note should be as clean as if you were alternate picking. It's best, like with most techniques, to start out slowly and add speed when it becomes comfortable. Look at the video of me playing these lines a couple of times through, while focusing only on my right hand angle. See how it changes just for the sweeping portions. Try angling your pick at slightly different angles for up sweeps, down sweeps, and alternate picking, to experiment and see what works best for you.