This isn't a new topic, and it has been discussed before. What I'd like to do is break things down "by the numbers" somewhat and see whether we can support one play over the other based on EV. Clearly, there will be greater risk/variance with smooth calling. Let's start with some examples:

AQ raises $2, I smooth call with KK: (Let's say a $5.25 post-flop pot with the dead money that's in there)

What can happen:
An ace could fold, I have to give it up: about %16 (-$2)
A queen could flop, I probably win a big pot %16 (+$15 or more)
An ace and a queen could flop, but I'd slowdown b/c of the ace. I don't lose my stack if AQx flops.
QQx could flop but that's very rare. I probably wouldn't lose my stack vs. that flop anyways.

AQ raises, I re-raise $5 with KK: ($11.25 post-flop)

He often folds, and I win it right there. (+$3.25)
If he calls, I get a few extra $ in the pot, BUT
16% of the time when the ace flops, I've invested more ( -$5)
16% of the time when the queen flops, I might win less because he now fears AA/KK as a threat. (Maybe average of +$10ish)
About the other 2/3 of the time he probably gives it up without much of a fight, but we've gained the extra money from the pre-flop re-raise (+$6.25 instead of +$3.25 if I hadn't re-raised)

So in the AQ vs. KK example, I like the smooth call overall IF A RE-RAISE IS LIKELY TO FOLD THEM because: You give them more chances to catch up and hit their ace, but you normally make up for that by winning more when they pair up their queen IMO. However, a re-raise is better if they will actually call it a large % of the time.

If the example was AQ vs. AA, smooth calling is even better since an ace flopping is great for you.

HOWEVER...

When it's pocket pair vs. pocket pair things change.

Let's look at 99 vs. KK.

A smooth call now gives them a free chance at a set. There's also a good chance that a set will take your entire stack when it hits.

So nearly 10% of the time you risk losing your stack with a smooth call. Is deception worth this?

Say a raggy flop comes down. How much more does 99 lose against you when they DON'T make their set compared to when you re-raised pre-flop and gave them a clue they might be beat?

I could post a bunch of other examples I've thought of, but I think I've come to this conclusion(s):

1. A smooth call pre-flop is good when you think your opponent likely has 2 face cards instead of a pocket pair. If your opponent's range of raising hands in this position includes many non-pairs, consider a smooth call. If your opponent is loose enough to call many pre-flop re-raises with hands that have 2 face cards, a re-raise is probably better.

2. A re-raise is good if your opponent's range of possible hands consists of mostly pocket pairs. There's more to lose here and less to gain with a smooth call. A re-raise is even better versus dummies who will call/raise your re-raise AND not really catch a clue that they should slow down post-flop if they flop an overpair yet get challenged by you.

3. A smooth call might be better versus tough competition where deception has more value, even if this means giving a lesser pocket pair a free chance to make a set. I keep thinking back to the FTR Showdown where Michael smooth called AvatarKava's QQ with AA and got him all-in on the flop. I bet that doesn't happen if he re-raised pre-flop.

Thoughts?