"On 11 January 2007, China conducted an anti-satellite missile test in which one of their FY-1C weather satellites was chosen as the target. The collision occurred at an altitude of 865 kilometres, when the satellite with a mass of 750 kilograms was struck in a head-on-collision by a kinetic payload traveling with a speed of 8 km/s (18,000 mph) in the opposite direction. The resulting debris orbits the Earth with a mean altitude above 850 kilometres, and will likely remain in orbit for decades or centuries.[18]" (https://en.wikipedia.org/wiki/Kessler_syndrome#Anti-satellit...)
Kessler syndrome requires the rate of debris creation be greater than the rate of clearing and the rate of clearing in higher orbits is very slow.
https://amostech.com/TechnicalPapers/2012/Orbital_Debris/NIK...
How much debris though? If I put orange juice in my coffee mug, after a few runs through the dishwasher there may technically be a few particles of orange juice left, but my taste buds probably won't collide with it.
To attempt extend your analogy: you might be confident that most of the juice was washed out of the mug after a few cycles set to scour, but if you are deathly allergic to any exposure to oranges, what's your risk tolerance?
Make sure you clean the dishwasher trap, as well. :)
That's the key question the whole matter hangs on, but there's no objective answer for it. Neil Armstrong privately estimated his chance for successfully returning to earth at 90%. That's alarmingly low! That's barely safer than Russian roulette.
Determining how much risk can be tolerated means figuring out how badly you want the thing. The more you want something, the more risk you can tolerate. Satellites are extremely important to our society, so governments would continue launching the satellites they value most, even if the expected lifespan of the satellite due to space debris was very short.
Of course, superfluous and casual use of space would grind to a halt. One of many casualties of war.
A head on collision would be incredibly violent and would disperse a large cloud of debris over a large area - some of that would fall back to earth quickly. This would be incredibly unlikely, given that most objects above Earth orbit in a relatively similar set of planes and inclinations. A more likely scenario would be two similarly inclined orbits overlapping, with the satellites or debris impacting shallowly and at relatively (to orbital velocities, that is) low energy. It wouldn't take much to shred apart much of the more delicate instrumentation orbiting above our heads, which would similarly endanger more sensitive equipment, and so on.
https://swfound.org/media/6575/swf_iridium_cosmos_collision_...
"Analysis by both NASA and outside experts indicates that more than half of the Iridium debris will remain in orbit for at least 100 years, and much of the Cosmos debris will remain in orbit at least 20 to thirty years."