In Omaha High-Low (AKA, Omaha 8-or-Better), a scoop is when one player wins the entire pot vs. splitting it. It can happen in two ways: the winner has both the best high and low hands or there is no qualifying low. There is always a high.
Let’s look at some approximate numbers.
Before any given Omaha deal, there is over a 60% chance of a low.
After that the chances of a low are:
2 low cards on the flop = 25% by the river
3 low cards on the flop = 40% by the river
4 low cards on the turn = 50% by the river
Now, win the high to scoop!
Note: Omaha is a relatively new game, first played in Las Vegas at the Golden Nugget in 1982. I grew up playing seven card stud high-low. Back then, a perfect low was A-2-3-4-6 (non-suited). Someone figured out it would make a more interesting game if a wheel (A-2-3-4-5 either suited or not) could qualify for a low hand.