Cash game players, particularly those playing in a live environment, are often competing in games that are deepstacked. Playing with deep stacks can be one of the most profitable forms of cash game poker, but fail to make some necessary adjustments and the complete opposite can be true.
The deeper the effective stacks are, the less we should be willing to get out chips in without the nuts.
Put your thinking cap on and imagine the following scenario. You are playing in a £1/£2 cash game at your local casino and everyone has at least 100 big blinds in their stack. You raise with a pair of eights in the cutoff seat and the villain in the big blind three-bets you. You call and the flop comes down A-8-5 rainbow - that is all different suits. This is a superb flop for our hand because we have flopped middle set and 100bb deep we should be looking to get our stack into the middle. However, would you still be as eager to get your money in if we were sat 200bb deep? What about 500bb or even 1,000bb deep?
The deeper the effective stacks are, the less we should be willing to get out chips in without the nuts. The main reason for this is the deeper the stacks are, the greater our reverse implied odds become and the chances of being on the wrong end of a "cooler" increase. Losing a 100bb stack set-over-set is painful, as is losing a king-high flush to an ace-high flush, but if you are 250bb or more deep than being stacked is definitely avoidable.
When we are playing deep stacked poker the having the nuts is even more powerful than usual. This means hands such as suited aces increase in value, simply because being able to have a better flush than an opponent with lots of chips behind is an amazing situation to find yourself in.
Likewise, big pairs become more valuable while low pairs lose some value. Although your odds of flopping a set are still the same as when you play "normal" stacked poker, the times you find yourself on the wrong side of a set-over-set scenario are so costly that you need to avoid being over-setted; or at least be more careful when you flop a set while deep stacked.
Another group of hands that are almost designed for deep stacked poker are suited connectors. While we have to be careful not to be over-flushed, suited connectors can make straights which are difficult to detect at the best of times, never mind when you have 300bb ready to go into the middle of the table!
Good players want to play against weaker players in deep stacked games because weaker players make more mistakes (such as committing tacks with non-nut hands) and these mistakes are emphasised when the stacks are deeper. Do not pay off the better players at any time, but especially not when you have much more to lose.