WORKING ACTS
In a sideshow, there is a hierarchy with the highest-paid performers being the natural-born freaks. Working Acts-- like sword swallowers, fire-eaters, magicians (especially)-- were considered interchangeable.
Every season the show needed a sword swallower, a fire eater, and a magician. The word would go out and often on the smaller shows the performer willing to work the cheapest got the job.
The genre of Working Acts also produced some very unusual performers whose eccentric skills could hardly be displayed anywhere other than the sideshow.