Victor,
I haven't read that book but I've been doing some due diligence on a publicly-traded brothel in Australia.
High-margin businesss (gross margin is 50%) and very strong cash flows in spite of few depreciable assets. Recurring revenue base (it's a service business). It would be perfect were it not for the limited per-customer service capacity. This is not really a scalable business, nor can it be really global, given all these silly regulations that differ by country. Of course, collective bargaining by employees is always a downside risk.
Unfortunately, this is a discretionary spending category for the consumer. All else equal, high petrol prices means fewer, um, "transactions."