On a Holley, if the fuel level is too high (floats set too high) gas may come out of the vent tube of the secondary bowl during braking and out of the primary bowl vent tube during acceleration. When all this un-metered gas hits the combustion chambers, the engine may flood & die. Even with the vent baffles or whistles, gas can still come out the vent tubes. For this reason, vent tube extensions are common on drag racing or off road racing cars.
If the fuel level is set way too low, as mentioned above, the jets may become uncovered during braking (primary side) or acceleration (secondary side). Or you can even run the bowls dry during full throttle if the float level is too low. The bowls are pretty large so this is more rare in my experiences.
I personally have more trouble with the "gas level too high" scenerios
Z. Ray