Kilts are relatively easy to care for. Wool, is a superior natural fibre that is inherently soil repelling. If you do get a spill or spot on the kilt, try to take care of it as soon as possible, and only resort to dry cleaning if you can't take care of it on your own, or if it is need of a general cleaning after a lot of use.
To take care of spots and spills, try brushing the kilt with a stiff brush after the spot has dried. If this does not do the trick, use a damp cloth and gently try spot cleaning until it goes away. If that fails, take it to the cleaner and pinpoint the spot(s) that you want taken care of.
With proper care, a kilt should last generations.