It can help briefly by masking it with minty freshness, but mouthwash kills bacteria in your mouth that cause bad breath. Since ketones are being released in your actual breath, mouthwash won't actually get rid of them. But the mouthwash or listerine strips will help if you need a quick fix for a kiss or a face-to-face conversation or something.

I find that if I drink tons of water, my breath definitely stays fresher.

I don't even mind the ketone breath, though. It's a fine trade-off for losing the weight!