Even without squirrels acorns drop before the leaves then fallen leaves cover them and provide a damp blanket where they can germinate.
Many acorns are high in tannins so taste terrible. Adaptation by the trees to try to reserve some seed for germination I guess.
Some species are lower in tannin and are better for feed. Acorns generally have very high calorific value. It is even thought that the high quality of jamón ibérico de bellota, a ham made in Iberia from pigs fed on a diet of acorns (and considered by many to be one of the finest hams in the world), is due to the high level of antioxidants in the acorns, which help to prevent lipid oxidation.
In some cultures and times acorns have been a staple food. Tannins are leached out of the nut meat in running water or by boiling in several changes of water. The result is nutritious food. Acorns appear to have been a major food source for native peoples of California and probably other parts of the Americas an a few other parts of the world.
Some species have low enough tannin levels to be OK for human consumption without treatment. I believe that the 'white' oaks have lowest tannin levels.
Acorns also yield oil and can be ground to flour for cooking.
Even sprouted acorns can be eaten. Germination changes the starches into sugars in the same way that sprouting barley to make malt changes the starch into fermentable sugars for brewing.
Although all that is interesting I have digressed a long way from germinating acorns for bonsai.
If you are worried about wasting soil and pots on acorns that may not sprout place the acorns in a plastic bag with a small amount of damp material - soil, compost, sawdust, newspaper, sand etc and close the bag. Check each week and remove any acorns that have produced a root. Plant those into pots of soil and watch them grow.
