Independent Radical wrote a great entry about the differences between pornographic sex and healthy sex.
For a sex act to be healthy and non-pornographic participants must enter into it with the intention of enjoying the act itself. In case this is not already clear, this enjoyment does not need to be purely physical. Those who have sex with people they love can experience emotional and, in some cases, intellectual enjoyment from their sexual activities. If one does not have affection for their partner, they should at least have positive feelings towards the sexual act. To pursue sex as a means to some other aim (e.g. economic resources, popularity, approval, self-esteem), like women in the sex industry do, is to increase the pornographic character of one’s sex life.
Opponents of the sex industry recognise that women who enter it often do so out of poverty and desperation, but economic concerns also influence sexual activities which occur outside the industry. Conservative men brag about how they provide money and other resources to their wives (who in turn provide them with sexual and domestic services), while mainstream culture promotes the gold-digger stereotype, as well as the belief that men who buy things for women are entitled to sex.Thus the view that women should trade sex for economic resources is not limited to the sex industry.