Mammillarias are easy to grow once you figure out that they really don't like to be over-watered and will react badly quickly if they are.
Not all Stapeliads have foul smelling flowers. The name Stapeliad refers to plants within the tribe of Stapeliae and includes lots of different Genera, including Stapelia. Stapelia are the ones with the reputation of smelling like rotting meat. I suggested this particular plant might be Caralluma sp., also a Stapeliad, but we really won't know until it blooms.
