Duplicate your background layer. With the background layer copy active, go to your Filter menu and choose Noise > Dust & Scratches. Set the Radius to 6 and Threshold to 0. Now go to Layer > Layer Mask > Hide All
In your layers pallette, click on the black mask that's linked to your background copy before proceeding.
Next select a soft edge brush, 150 px in size with opacity set in the 40% - 50% range, and white as your color.
Begin painting over speckled areas of the photo only with a minimalist's eye. Accept that it'll never be perfect.
Now that you have the general idea you should re-do it, experimenting with your own brush settings, D&S values, etc. Once you're happy with things, save your improved image, including layers, in the .PSD or TIF format. If preserving layers isn't important, save the image to a single layer format like .JPG or .PNG. Hope this helps.
Why do dark objects, like tuxedos become speckled?
It's not just the dark objects that are speckled. Your entire photo is speckled. This usually happens because the original print and your scanner glass contained a lot of dust that is reflected and picked up by the sensors when the scan is made. There are products that are available to clean your prints before scanning as well as to clean your scanner.