Oh hello Trevaunance, I agree with you :-)
Its worth looking at Kinsey's research for all its faults. Its relatively common for straight people to have had a bit of a dabble with the same sex and for gay people to experience the opposite sex. IMHO applying the bisexual label to everyone whose experience falls somewhere between completely straight and completely gay doesn't help very much. On one level it might help categorize a particular sexual experience but it doesn't necessarily shed much light on the person's sexuality. Really its about the people involved and what feels right at the time. So I agree with mrkinkymrsbi comment. Search Kinsey Scale.
Prostitution was decriminalised in New Zealand in 2003 ... and we have not gone to hell in a hand basket. There are still problems and some local politicians in particular do not want to accept it, but the general consensus is that it has made things safer for working girls and it has not lead to an increase in prostitution.