How do you guys tell if a guy is just being nice or if he's flirting with you?

Basically title since my situation is a little stranger than most. I also convince myself that he's just bring nice.Context:I'm 20, never been in a relationship and a leukemia patient (though, basically in remission, meaning there aren't any cancerous cells left), and I'm pretty friendly with all the nurses, easy-going and reletively independent when I'm admitted. They all talk to me and I'm pretty open with how I'm feeling and what I'm up to. General questions I usually get are:*How are you feeling?*How's your day?*I heard you weren't here for x period of time, how was that?*So what were you doing before you got diagnosed?Among the staff and occasional nursing students from the local joint university/college program, there are a handful of guys. One of the nurses had me and when he was hooking my IV up he asked me about one of my interests. He only asked me if I was interested in anime, but it strikes me as odd because none of the other nurses ask me about anything other than things they need to know about for the purpose of their jobs.He also came to look for me once just to tell me what chemo I had coming up, but he also has a nursing partner and he's more experienced of the two ( I often hear her asking him for clarification or getting him to come and help her before she does some tasks), so he easily could of asked her to look for me instead of coming himself.When I'm not on his service, but another patient in my room is, he usually drops by and says hi with a quick how are you, but this one I think he's just being nice. I dunno, maybe I'm just reading into it too much. Also doesn't help that I've been really wanting a relationship recently.Though aside from my situation, how do you guys tell that a guy is flirting with you in other social contexts?PS. Doing this from mobile, so here's to hoping the first draft formats well!