Where is the line between chasing a girl who is playing "hard-to-get" and a girl who is a dead end?

You could usually tell a girl is not interested if she.. doesn't show any interest.
Just pay attention to her actions/behavior.
Even girls who play hard to get can't hide how they really feel sometimes. Like, happiness, sadness, disappointment, anger...
Some signs:
-She sounds happy when you call. Or you can sense a smile on her face when she hears your voice.
-She is interested in what you have to say. Your opinions, your stories, your life.
-She asks if you're ok. Or she notices there is something bothering you.
-She gets upset (or quiet) at you. -- when a girl gets upset about something you did or didn't do, it means she actually gives a sh**.
Not interested:
-She forgot what you said 2 mins ago.
-Checks out other men.
-Constantly checks her phone, texts, calls, etc when you are together.
-When you call her, she sounds annoyed. You can sense she wants to hang up asap.
-She is NEVER available, even when you try to make plans with her 3 weeks in advance.
-She just doesn't seem to care.
Of course there are more signs, but those are just some examples that girls (even those who play hard to get) will do when their not interested.

I think a lot of men have defined being interested as: Calling all time; Texting every minute; ALWAYS wanting to go out; Always available when he calls; Always available for a last minute date; etc. --Some men misinterpret "hard-to-get" from "PLAYING-hard-to-get"--
Women have a lot going on. Women are busy people too. But even the busiest women know how to show some kind of appreciation to a guy they are interested in. They don't play games, they just keep you working for her, and lets you know she is not easy. But if for some reason they make you feel like crap. Or they make you feel like you don't exist... then they're pretty much not interested. And that applies to every woman.

I don't understand why you would go for a girl who plays hard to get. Doesn't that mean, a lot of mind games, drama, and... confusion? The games never stop for girls who "play"-hard-to-get.

Just don't confuse those who Play hard to get, from those who are not easy to get. haha I know it's confusing.

if it's a girl you've already met and gone out with, she would only turn you down if she doesn't like you, unless it's an exception. If she keeps blowing you off (more than once), she's probably not that into you. Girls absolutely adore the men they like and would never turn them down. If she has finals or work, she'll fit you in somehow within a few days at most.

A girl who is not interested isn't playing. She will make no signs of interest at all other than politeness.

Hard to get is still showing that you're interested, but just not being extremely forward. It's a way that some girls use to protect themselves until they are sure of the guy's intentions. She might seem shy but she will still show some signs, she just won't be all up in your face about it

is this too' has a point. She should give you SOME sort of feedback! I know with me, sometimes I really am interested in the guy and I don't totally give him much of a response... That's usually for one of two reasons:

1. He seems to be the type of guy that flirts with a lot of girls and I don't think he sees me any different.
2. I'm going through something and he seems like wants to take more when I don't have anything to give.

Otherwise, I just don't like him. :|

Oh, and you don't have to answer every question a woman asks you ;)

I believe the answer to your final question is this... You cross the line when she vehemently told you how she feels, never(ever) responds to your texts or phone calls or email - whatever, and if when you see her somewhere (like if your and her friends hang out together and you both happen to be there too) she totally walks the other way or doesn't make eye contact or is just beyond rude.

p.s. Some girls will do that to guys anyway...but they're sadists.

I don't know if there is such a line. And I don't care.

Because if I express interest two or three times and the girl doesn't reciprocate, I move on. I don't care about her motives. I want to date girls who want to date me, and I don't waste my time on girls who don't make time for me.

For one, you know a girl likes you if she makes up what us guys see as an excuse, which may not be, and then calls you back, or says maybe we can hang out some other time. That means she's interested and is sincerely telling you the truth about her situation.

Generally...you can give them chances to show you if they are a dead end...you can only try so much before you realize its a waste of time. Some girls live off the attention, while some don't know what they want...and so on...the enigma continues...I'm currently wrapped in one myself...where the girl pursued me, and now says she needs space...what will kill you is beating your thoughts to death. Take it all at face value...don't read into anything endlessly...and the truth will eventually come to light.

it's hard to tell, but there should be at least some signal (or in case of chasing girls, there should be some rewards/feedback from her). In the end, relationship is a 2 way street, and if you're not happy with what you're doing, and there are no rewards out of the process, STOP DOING IT!