Hi! I know a lot about plastic surgery because of my job, so I'll give my 2 cents.
I often saw in this thread you guys assuming some actresses' breasts are real because they bounce, jiggle, are soft or have no scars.
I'm going to break some hearts here, but none of these ensure breasts are not enhanced.
Sure, it can help a lot with spotting the more obvious, poorly done boob jobs. But it's definitely not a given.
Why?
First off, let's start with the bounce.
Fake breasts and natural breasts bounce, both of them.
They might not bounce in the same way, but fake boobs most definitely bounce, and in fact they often bounce more than natural ones for the sheer fact that they tend to be bigger. Bigger mass in most cases equals more bounce.
Of course, some fake breasts don't bounce and are extremely stiff, but that definitely doesn't go for all implants.
There are two (main) reasons why some boob jobs are hard, balloon-like and do not bounce or jiggle.
It's either:
1- Because the woman went for a size that is way too big, which pushed and spread out the natural tissue she had beyond its limits.
2- Capsular contracture. This is a well-known complication of boob jobs that do not present itself in all breast augmentations but only in a minority of them.
Essentially, all women who get implants have their bodies create a layer of scar tissue around it. It's a defense mechanism of the body.
If this scar tissue is thin, the breasts will look, feel and move softly and naturally. But if said scar tissue is thick and hard, then the implants will also harden and give the stiff, obvious boob job look to the breasts.
These two factors as I mentioned also impact jiggliness, not only bounce.
Implants can definitely jiggle, given the procedure was done well and there are no complications.
Why can they jiggle?
Well, not all women who get breast augmentation are entirely flat chested.
Since being 100% flat chested is pretty rare, most of them have at least some natural breast tissue. That natural breast tissue will cover the implants and jiggle at least a bit, especially if the breasts were already around at least a B cup to start with (which is a very common natural breast size).
Even women who have little to no natural breast tissue can still get a jiggly look with implants, through hybrid breast augmentation. It combines fat transfer with implants, with the fat acting as both further added volume and providing a natural coverage for the implants, that are of course harder than fat.
Add this to the fact implants are not very hard per se. They are actually not even hard. They only harden in the case of capsular contracture.
Most implants are quite soft, with the newer generation ones being even softer and able to simulate the feel and look of natural breast tissue pretty well.
Lastly, scars.
The quality of implants isn't the only advancement in breast enhancement plastic surgery, scars are another one. Incisions do not need to be big anymore, leaving big noticeable scars.
And, as many people already pointed out, some incisions are done in the armpit, so even if there is no visible scarring around the nipples or under the breasts, that doesn't mean a procedure wasn't performed.
Another very subtle, but to be fair quite rare, incision site for implants (that as all incisions leaves scars) is in the lower tummy. So again, they could have gotten that type which would not be visible on the breasts.
Either way, scars fade. With proper care and with lasers, they can fade a lot and be barely visible. And if they don't, filters and make-up exist and are used a lot in porn.
Nothing forbids a JAV actress from applying a product that will cover her scar from breast augmentation during shooting, same way she would cover a pimple with foundation.