Ladder is warped; how much is too much?
If the ladder sections (base and extension) are not square and plum to each other there is a chance that it will not preform safely. Depending on how much deviation there is between the two sections you should be very cautious when using the ladder fully extended.  The top extension is secured and guided by an inter-locking rail built into the bottom ladder. If the guide is not straight and true there is a possibility for failure (accident). Again this is dependent on how great the warp is.  Fiberglass ladder's can be cleaned similarly when cleaning any fiberglass material (hot tubs, boat hulls, etc.). Using a 220-300 grit Wet/Dry sandpaper and backing block wet the section to be cleaned and gently, at first, work the paper rinsing occasionally. If needed change to the next highest grit.