People tend to describe a driveway as dirty, singular. It almost never is. Walk out and look properly and you will usually find three or four different problems sitting on the same slab, and they do not all respond to the same thing.
The grey that is actually alive
The broad, even darkening across an older driveway is usually organic — algae, mildew, the thin biological film that grows anywhere in East Texas that stays damp. It is worst on the north side, under trees, and along the edge where the lawn sprinklers reach.
This is the satisfying one. It lifts with a cleaning solution and comes off in a single pass, and because the solution kills the growth rather than just knocking it loose, it stays gone considerably longer than a rinse.
The orange that is rust
Distinct orange-brown blooms, often in a fan shape, usually mean well water or a sprinkler head throwing iron-bearing water across the concrete. Sometimes it is a steel planter, a wrought-iron chair, or rebar too close to the surface.
Rust is a chemical problem, not a dirt problem. Pressure will not move it. It needs a rust-specific treatment, and it will come straight back if nobody adjusts the sprinkler head that caused it.
The dark patches that are oil
Oil and transmission fluid soak into concrete rather than sitting on it. How much comes out depends mostly on how long it has been there. A fresh drip usually lifts almost completely. A stain that has been feeding the same spot for six years has gone deep into the pores, and honestly, you are looking at a significant improvement rather than a disappearance.
The lines nobody notices until they are gone
Tire marks, mower tracks, the darker path where everyone walks from the car to the door. You stop seeing these because they arrived gradually. They are also the ones people mention afterwards, because the driveway suddenly reads as one even surface again instead of a map of everyone’s habits.
What this means for the estimate
It means anyone who quotes a driveway without looking at it is guessing. The organic growth and the traffic marks are ordinary work. Rust and old oil are extra steps with a different treatment and, sometimes, a frank conversation about how far it will actually come.
We would rather have that conversation before we start than have you walk out afterwards expecting a slab that looks poured last week.
One thing worth doing yourself
Go and look at where your sprinkler heads are pointing. If one of them is watering your concrete instead of your grass, it is going to keep making the same stain no matter how many times anyone cleans it off.