Men who are buying sex through prostitution are then rating the woman online like a product.
Research presented by UCD researcher Ruth Breslin shows the majority who are engaging in the activity are well educated and are mostly married or in a relationship.
It's part of a conference held by the Men's Development Network on changing men and boys' attitudes.
Ruth Breslin analysed thousands of reviews on these websites.
"They are very much rating the women like a product or service because they are rating her out of five stars on a range of different variables such as things like her appearance, the satisfaction she gave them, the value for money and so on."
She says there were some apparent themes from the reviews
"Having read these several thousand reviews, we analysed some of the themes and patterns that were coming out of those.
"What we found and probably won't surprise you, that when men are talking about their purchase of sex, they are motivated by a strong sense of male sexual entitlement, that this is something they are entitled, that this is a product or service that they can avail of."
