There is a group of barn cleaners in Portland, OR area but you wont find them on the internet. The guy that runs the service simply stops in and asks barn owners if they want to pay for his crew to do the work. A lot of the more expensive stables pay the service (charges on a per job basis). The lower cost barns don't pay for the service. I was around a barn that used this service for a while and this is what I observed.
-Since they get paid per job they work real quick and often way to quick. Good luck getting them to return and finish a job right that day, you'll see them again tomorrow. It's also not unusual to see them show up with "help" that hasn't been shown the way you want the job done.
-Outside of the guy who runs the service, most don't speak english or have very limited ability to speak english. This plays into the first problem, bit tough to explain what they are doing wrong or if you want to get them to do something else. Pantomining can only get you so far.
-When you get a good one they tend to disappear on you. Often because they've found another job but sometimes because ICE has caught up with them (illegals aliens for those who don't know what ICE is).