Well, I have a few times, for help around the house and the ranch. There wasn't any sort of sex involved. It was a way to leverage unused rooms to pay, in part, for help. Not much different from how farm hands have been compensated around here for generations. Or from renting out a spare room for cash. The only difference is that by seeking out a gay
assistant, you don't have to worry (well, not too much anyway) about offending him/her with certain aspects of your lifestyle.
Overall, it is probably less hassle, if somewhat more expensive (maybe), to simply hire local live-out help that goes home at the end of the day.
Beware also, that many, if not most, of the guys who advertise "houseboy" services are simply hustlers. (And probably most of the guys seeking them are simply johns.) Yeah, that
once led to an interview that was confusing and embarrassing on all sides.