This is totally more convenient than carrying a small toothbrush/toothpaste with me, a bottle of mouthwash, or uh, some breath mints. And at $24, I'm sure that eventually, after a few years, it'd be even cheaper than carrying some of those are you, too. I think...maybe....
Nonetheless, it's kind of a cool idea and might be cute as a gag gift. Or as a wedding gift for the newly weds who haven't quite grown to except morning breath yet. Or hey, Valentine's Day is really right around the corner, so this might be a funny gift...or gentle nudge, heh.
(Oh, and as a side note, when I was reading the description:
Instead, breathe into the Kiss-o-Meter, a compact "bad breath detector" with heart-shaped indicators to let you know if you're pleasant enough for smooching. Five different outcomes are possible: Kiss me, Possible, Maybe, Risky, and Never. Imported. Wipe clean.
I skimmed across and read "imported" as one of the possible outcomes and all sorts of thoughts ran through my head....)