Slip casting is a technique for making multiple, essentially identical, pots inexpensively. Slip casting and jiggering/jolleying are the ways most commercial dinnerware is made today. In slip casting, a suspension of clay in water is poured into a plaster mold and allowed to sit. Water is absorbed into the mold and clay is deposited on the interior surface of the mold. When the mold is emptied and opened a slip cast pot is removed. Slip casting is used by some potters to inexpensively reproduce a pot which is extremely time consuming (and therefore expensive) to make from scratch. Some potters also use slip casting to make a difficult part (e.g. a complex spout) for an otherwise hand-made pot. It is a very legitimate technique when it is clear that slip casting is the process that has been used. Unfortunately there is a tiny minority of potters who will try to pass off slip cast pots (and even slip cast pots that are made from commercial molds) as hand made pots. If a potter's pots look identical to one-another, ask if they are hand made or slip cast. If they are slip cast ask whether he or she made the mold from one of their originals or whether it is made from a commercial mold. You can almost always tell a slip cast pot by looking for mold seams that have not been removed on the underside or inside surfaces of a pot. I don't currently use slip casting as a technique; although I have experimented with it and can appreciate its advantages in certain situations. The main issue with slip casting is one of integrity. If a potter is open and honest about using slip casting and his/her prices reflect this high productivity way to make duplicates cheaply, fine. If the potter is trying to conceal use of the technique or, worse, is using it to copy someone else's work, it is, in my opinion, an unethical or fraudulent practice.