There are some nice erotic massage studios in Ghent, mostly Thai massage (surprise, surprise) which are quite popular and offer top notch service: a full body massage with a happy ending costs around 80€, while full service is subject to negotiation. Most individual erotic masseuses will advertise on directories like Redlights (https://www.redlights.be/) where everyone can find something suited for their tastes.
My personal favorite is a studio. In my opinion, a small spa where someone has invested their time and money into the interiors and atmosphere will always beat someone’s apartment.
The salon Soda Massage located on Waaistraat 16 falls definitely into the non-erotic category. It has a whole basement turned into a mini spa, there’s nothing better after a week of hard work. Most Thai massage parlors are located around the train station.