All you have to do with the Tanita ES-100 is turn it on, flip out the sensor and point it to a part of your body you're concerned is exuding too much musk. It measures particulate matter and after 10 seconds, will display how intense your odor is on a 0-10 scale (0, you don't smell; 10, you don't have friends). Level 5 and above means it's time for "smell care," though it might be more effective if it just told you to take a dang shower.
The stench scale goes both ways: if you've applied too much deodorant or cologne, the pocket-sized ES-100 will let you know if you should tone down the aftershave a little. The replaceable sensor is good for 2,000 uses, or about a year.
Tanita reckons salarymen in their 40s and 50s will be most interested in the ES-100, as that's when the company expects men mostly start worrying about how much they stink. Seemingly, anyone who is not a middle-aged man doesn't give a hoot whose nostrils they're offending.
The ES-100 goes on sale in Japan Sunday, and Tanita is selling it for 13,824 yen ($125). That seems a touch pricey, though it's less expensive than a similar Bluetooth device that hit the market last year. Still, it'll be totally worth it if packed Tokyo trains smell a whole lot nicer in the middle of summer.