From the study linked in the OP:
According to evidence submitted to the UK Government (Home Office, 2004), between 50-75% of women entered prostitution before they were 18, with 15 years being the average age of entry.
In fact, an overwhelming majority of women in all forms of prostitution have been sexually abused as children (Silbert and Pines, 1982a; Nadon et al., 1998). Some estimates are as high as 90%.
Research has shown that there is a 75% rate of current or past homelessness among those prostituted in nine countries (Farley et al., 2003).
There is extensive literature documenting that prostitution causes profound emotional damage (Baldwin, 1992; Barry, 1995; Dworkin, 1997; Herman, 2003; Hoigard and Finstad, 1986; Farley et al., 2003; Raymond et al., 2002).
As a result of sexual exploitation and violence before and during prostitution, women, men and the transgendered in prostitution are known to suffer from depression, traumatic stress and other anxiety disorders, dissociative disorders, eating disorders and others (Farley et al., 2003).
Watts and Zimmerman (2002) at the Department of Public Health and Policy of the London School of Hygiene and Tropical Medicine noted that trafficking for prostitution and violence against prostitutes was one of the most common and severe forms of violence against women in the world (2002). A study of 240 women prostituted in Leeds, Edinburgh, and Glasgow found that 26% of women in indoor prostitution had experienced some form of serious violence from the men who had bought them in the past six months (Church et al., 2001).
Studies by Anderson and O?Connell Davidson (2003) and Di Nicola et al (2009) report that most men who buy sex are aware of and have witnessed exploitation, coercion and trafficking but this does not affect their decision to buy sex.
so let's not believe they're all happy hookers, eh?