Presumably she did get paid something at the time and this took place in Lake Tahoe, California. Definitely illegal in California. It's not legal in Stateline Nevada, or even in Reno. You have to go out into the boonies of Nevada to find legal bordellos.
But what is a rich guy to do when his Slovenian mail-order bride is all stretched out by his little scion's arrival?
The funny thing is that it is legal to screw a hooker if you film it! Then you are just making a porno, which is a whole legitimate industry in the LA area.