When an opponent routinely selects particular ranks or suits from the discard pile, for instance, it can be a sign that they are attempting to make a partirummy gkeecular meld. In these situations, it might be prudent to keep cards that could help them finish their hands from being discarded. On the other hand, you might have a chance to play more aggressively if your opponent shows signs of having trouble with their hand, such as discarding high-value cards frequently.
