They won't help you see better in murky water, so don't expect that.
They can't hurt, and after wearing cheapo clip-ons for years, I finally plunked down $450 for prescription polarized sunglasses. That was mostly because I bought a convertible last Fall, however.
I have been able to see fish with polarized sunglasses that were invisible when the sunglasses were removed. You're still going to have to look carefully, but they do help. You'll still need to know where the likely spots are on a stream, and be careful not to get too close while using your new X-Ray vision goggles.
Being able to see the bottom while wading is a great help. I've posted that my wife slipped and broke her ankle two years ago, and that was in less than a foot of water, so it's not just the deeper spots that pose a danger.