Regulating sex work

In June of 2003, New Zealand decriminalized prostitution. As a result, the industry fell under the aegis of the NZ Occupational Safety and Health Service who have produced a guide. The guide is an odd mix of the bureaucratic and suggestive. Here's a sample:

In situations where more than one worker is providing service to a client (e.g. threesomes) it is necessary to ensure that equipment such as vibrators and dildos is not used by one person and then another without being cleaned, disinfected and having a new condom put on first. Ideally each worker should have her/his own toys and equipment, which are not used by other workers. Each worker may choose to use a condom of a different colour in order to identify who has used the dildo last.

Excellent advice! Can you imagine a US bureaucracy producing a similar guide? Do you recall what happened to Jocelyn Elders? Alas, the New Zealanders are not so liberal with regard to other policies - you can go to a brothel, for example, but don't try lighting up after sex or you will be in contravention of the law.

All of this reminds me of the following IQ test question:

What is the minimum number of condoms required for safe sex in each case:
(a) two men with two women
(b) one man with three women or three men with one woman
(c) three men with each other
(d) 2k+1 men with one woman
(e) m men and n women

Is there anyone in the world smart enough to figure out the answer and lucky enough to find the knowledge useful? Answers here in case you are simply lucky.

Addendum: Tyler also wrote about condoms recently. I promise we will get back to economics soon. Of course, the great Richard Posner did write a whole book about sex so we have strong precedent for these discussions. More information on the regulation of prostitution can be found at Wikipedia. Thanks to Eric Crampton for the link.