Two different questions wearing the same face
Somebody standing on a dull, stained, or discolored slab and somebody standing on a cracked, sunken one both end up asking a version of the same question, but they are asking about two different problems. One is cosmetic. The other is structural. Getting the diagnosis right matters more than anything you do next, because the fix for one does nothing for the other.
The quick way to tell them apart is to check for movement, not just for ugliness. Run a hand across the surface and look along the length of the slab. If it is flat, level, and just tired looking, you are almost certainly in the cosmetic category. If one side of a crack sits higher than the other, a corner has dropped, or a panel rocks under your foot, the ground underneath has moved, and that is a different conversation.
When it is just dirty, stained, or faded
A flat slab that has lost its shine usually lost it to the sun, to years of foot traffic, or to a sealer that wore off long ago and was never replaced. Concrete without any sealer left on it looks chalky and dull even when nothing structural is wrong with it, and it stains easily because nothing is protecting the surface pores from grease, leaf tannin, or rust from a planter.
This is the easy version. A wash and a fresh coat of sealer brings back real depth in the color and the surface sheen, and on plain broom finished concrete that is often the whole job. Efflorescence, a chalky salt bloom that can work its way out of concrete, is another common cause of a tired looking surface, and it usually washes off and clears up on its own without any structural concern behind it.
When a thin resurfacing layer can help
A resurfacer is a thin cementitious layer applied over existing concrete to renew a worn or lightly damaged surface. It has a real place, but only on a sound slab, one sitting flat on good ground with a worn top surface and enough grade left over to take the extra thickness without changing where a door swings or a step lands. On a slab like that, a resurfacer can genuinely bring back a like-new look.
It is not a fix for everything that looks old, and we will tell you plainly when a slab does not qualify. If the surface has flaked deep enough to expose the stone in the mix, or the slab has been through repeated freeze and thaw damage on top of an already weak surface, a thin layer over it is not going to hold.
When the ground underneath is the real problem
None of the above applies to a slab that is moving. A cracked corner that has settled, a panel that rocks, or surface flaking severe enough to reach the reinforcement inside it usually means the base underneath gave way, and a coating over the top does not fix a base that has already failed. Pouring a fresh layer over a slab like that raises the finished grade and repeats the same failure within a season or two.
That is a tear out and replacement conversation, not a resurfacing one, and it has its own page that walks through how removal, base repair, and the new pour actually work. If you are not sure which category your slab falls into, that is exactly what the estimate visit is for. We look at the ground, not just the surface.