Erotic massage parlors in Yerevan are usually ran by older women who are not necessarily interested in a sensual massage. Their reputation is rather nasty as well. People say that the majority of rub and tugs in Yerevan are brothels owned by the mafia. Freelancers like Anita (https://www.facebook.com/anita.srah) and studios like Evita Spa (https://www.facebook.com/massaje.salon/) advertise on Facebook, the Russian equivalent VKontakte or Odnoklassniki.
Egoist (http://egoistmassage.am/) at Movses Khorenatsi 90 is one of the more professional massage salons in Yerevan. An hour shouldn't cost you more than $100.