my ex used to do that! he did it when he was with me and i didn't find out about it until after we broke up, when he was doing it with his new girlfriend too. she found out and got really upset.
i think it's weird and i wouldn't have been ok with my ex doing it, but that's because he was a cheater. if it's just quizzes it's one thing, but making an account with like a photo and filling out the information and talking to people is kind of crossing the line for me.