Because they don't get to bathe very often.
That's the word straight from somebody in the business, a friend who works at one of the major TV studios, a production assistant who helps set up on-air interviews with economic experts. Japanese work culture in general is so severe and unforgiving, the T.V. industry in particular so competitive and cutthroat, program budgets and schedules so tight, that shows are completed in a blur of pain, stress and sleeplessness.
While the celebrites that appear on gameshows and talkshows are fresh to the studio, scrubbed and glistening with forced smiles, for the people behind the cameras it's another story. Sound and camera operators, decorators, makeup artists, production assistants, editors and directors often do 48 hour shifts. My friend described a scene where one of the floor staff, crying, begged the director for a few hours off so she could go home and sleep, as she had been working 70 hours straight. She was refused and told to work harder.
As well as a lack of sleep, production staff often have no time to eat or bathe. They live off cigarettes, coffee, and drugs. They run frantically around studios like haggard shambling zombies on meth, lurching from one excruciating deadline to the next. Mental breakdowns due to stress, fatigue and ill-health are common.
And in the Japanese summer, they start to reek pretty quick. It is not unusual for first-time 'talents' just being introduced to the business to recoil from the stench when they encounter production staff for the first time.
That's what I remember when I am exposed to the thick ocean of silliness that pours out of the tube into my living room. That's what I can't help but picture. That just off-screen, behind the camera and off to the sides, is a small army of walking undead, cadaverous and gaunt, their eyes ringed with black weariness and a homeless-like stench of sweat, stress and despair coming off them in waves.