Men do not know how to flirt if all you are getting is a sign they want sex. Flirting is an art form of personality and body language working together to give the giver all the advantage they need to attract the person they pursue. But when a guy makes it so obvious that his overall objective is to have a sexual experience rather than to just get to know you as an individual with intelligence and a creative mind, he has missed the point of flirting. A strong red flag to run away. You can not change him. He already blew his chance with you unless he acknowledges his flaw and wants to change it.
Time to change your game plan and meet guys in a different way. Personal sites are not the best way to meet men. Try meetup groups or Church groups. They may be more sincere.