Well my ex said so. I'm a football fan and often have some in depth discussions about it, music too on occasion. I'll chat to people on public transport if a conversation arises naturally but don't expect to see them again.
My ex said this can be construed as flirting. I think it's nonsense. I don't talk about anything else but the topic, never about personal things and I really am useless at flirting. I don't see how football chat translates into I want to get jiggy with you.