One thing you can say about poker players is that they love to be tricky and “outsmart” their opponents. This is the reason so many players slow play their big hands, even though it's often not the most profitable play. In Omaha High Low, while slow playing does occasionally have merit, it is not a strategy that should be employed often.
The reason people slow play is to increase the size of the pot. They are trying to capitalize on their implied weakness to get an opponent to bet for them. There are two major problems in slow playing in Omaha 8. First, while your hand may be the nuts at the present moment, Omaha 8 is a game of draws and before it is all said and done, you could have a losing hand. Don't give your opponents the opportunity to hit their card(s) for free. Sure they will hit their draw occasionally, but make them pay for the times they don't.
People on draws in Omaha are likely to do two things and neither one of them is bet when it's checked to them (it's call a bet or check behind). Second is the fact that Omaha High Low is a drawing game by nature and as such people are much more likely to call bets than they would in another type of poker game. If you know you are going to get action on your hand, there is no reason to not bet. Besides, there will be times where people will raise with hands like low draws and second best hands that will increase the size of the pot for you.
That being said, there are times where slow playing is correct.
• One example is when you flop the nuts and there has been betting and raising before it gets to you. Putting in a third or fourth bet here is unnecessary as they are likely going to do it for you and you want to be able to put in a raise on the turn when the limits double.
• Another example is when you are positive your opponent is going to bet. If you have a maniac or loose aggressive player at the table that bets any time it is checked to him, there is no harm in checking in order to get other people invested in the pot and then raising when it gets back to you.
• The last example of course is when you flop an unbeatable hand like quads or a straight flush. Even in these instances, however, because of the calling nature of Omaha High Low, you'll probably make more money by betting than by hoping for the check-raise.