We all sell the use of our body in a sense; the difference in professions relate to whether and how they are stigmatised.
When one takes a job under a capitalist system they are contracting out their body for certain periods of time. This is more visible in jobs involving manual labour. The distinction when condemning prostitution, therefore, is constructed on prejudice against jobs involving female sexuality, rather than an issue contracting out the body as a whole.
Our bodies do not wholly make up our ‘selves’; there is far more to a person than their capacity as a sexual being.
Additionally, if we see the sale of sex as inherently negative as it is part of the ‘self’, we then have an obligation to also see profit from creative endeavours as negative, for instance, given that they represent the artist's self. Additionally, sex workers sell sexual services rather than their bodies themselves.