I currently have none in my collection, but I think of re-introducing them into my garden, as either potted plants or grown from seed.
My experience is as follows: In a shaded location, they grow sparsely, with offsets wide apart, and lax stems. This happens even when there is bright but indirect light. In sunny locations, they are more compact, but pretty much scorched and with a barky texture (with Stapelia Grandiflora being the prime example). They still grow but they appear very stressed. When I buy them, they are mostly compact and healthy. This problem is the same with the smaller genera, like Orbea, Huernia and Caralluma. Here is a Stapelia PIC1, and a smaller species PIC2 from different websites. That's how they look when I buy them, but overtime, they grow differently, one way or the other.
So how are they kept that way? What other factors to consider?