Most of the time "warped rotors" aren't. If someone tells you they are ask them to show you a dial indicator proving there is runout in the rotor surface. Betcha there isn't UNLESS someone did a brake job and didn't clean the mating surface of the hub and rotor, and thus torqued it down while "bending" it.
99% of the time on a street vehicle what you have is uneven deposition of pad material on the rotor, which is a function of improper (or no) bedding on the brakes. Then you get them good and hot before an even transfer of material has happened and STOP with the pads up against the rotor, which deposits a nice heavy layer right there, and that now has a higher coefficient of friction than the rest. The result -- a "pulsing" feel to your stopping, and it gets worse over time because where the friction is highest so is the heat so you get even MORE uneven deposits.
If you catch it before crystalline changes happen in the rotor you can scrub it off with a stainless steel wire brush and then go properly bed the brakes. Once the iron of the rotor has its crystalline structure altered unevenly, however, the only fix is to replace the rotor(s) that are impacted as it will happen again if you don't because the coefficient of friction of the metal is no longer even across the entire surface.