+1 There are so many variables to take into account. There are objective ones such as effective stacks or ratios and then there are even psychological ones such as the opponent play-style or tells if you can spot and interpret them. Poker is so much more than just your two hole cards in the hand, so it makes this question tough to answer.
Correct again, in large part because people sometimes overplay the low pocket pairs. I'm sure blueskies knows what I'm about to say, so I'll re-word it for the op and everyone else here. What is basically being said is that smaller pocket pairs are less likely to realize their equity by showdown.
wut?
That still sounds jargon-heavy. Rewording it again, let us imagine we have a low pocket pair like pocket 4s. Say 4 of hearts and 4 of diamonds (4h4d). Okay, sure; I think everyone knows their hand is probably good if they hit a set (three of a kind with a pocket pair). What happens when you don't hit a 4 on the Flop though? That will be most of the time!
If the Flop comes something like:
5hJdKs (5 of hearts, Jack of diamonds, King of spades, rainbow Flop [all different suits])
or
2c6hAs (2 of clubs, 6 of hearts Ace of Spades) etc.
now is our low pocket pair any good?
Hard to say. Depends on many factors such as our position or the player tendencies we face, but just by the math alone - someone probably has us beat. Even if our low pocket pair is ahead now, overcards are basically every card (since our holdings are low) and we might be outdrawn - worse, we might even get bluffed off of the hand! For this reason, many players just won't deal with lower pocket pairs at all. Some play them, but instantly fold to any bet if they don't hit a set on the Flop. Some adapt based on position (playing more pairs in later position), but even here there is no way of knowing for sure if the hand is good. Even if you hit your set, you can lose to a better hand and a low pair needs to even think about higher sets the opponent may have hit (although unlikely).
Sure, the same could be said for AK - Villain might hold AA
However, it is less likely hands like AK are crushed and the player might convince themselves into continuing in the hand. This is the tip of the iceberg, but poker isn't so straight-forward.
Probably the most popular way to play low pocket pairs. Poker is too complex to say if this strategy is best or not, but it depends on many factors. Perhaps that is what makes the pros better than us; they all seem to have studied the game (or simply have so much experience playing) so much that they almost intuitively know when to adapt and go against the general principles of what we expect should be doing.