Seeing all the trouble with blank tank level gauges makes you wonder how the generations before us coped. They didn't have gauges and I don't personally know any who made any effort to clean their blank tank either. Just dump, leave, and repeat as necessary. Why do people want their black tanks to be clean inside?
But then I'm considering the folk like I camped with back in the day who were never parked in one place more than a week. Maybe it's more important for someone who stays in a rig that doesn't move for months at a time.