I think we have all had someone that we have met and thought, ok we will see what happens. Then the texts, calls, and even him showing up to places that you are at. It normally doesn't take long to figure out someone who is a clingy person. They will text or call you multiple times a day and its normally about nothing or what you are doing or more importantly where you are.
I have dealt with a few five stage clingers and I have learned ignoring doesn't always work. Sometimes you may have to block their number or even talk to them and tell them you will never want to be with them. Of course most people do not want to have the uncomfortable conversation to reject someone. So I recommend doing it through a text message or even an email. And if it still takes them a moment to get the point then block them!
I have two friends right now dealing with a five stage clinger. One is a guy and the other is a girl. My guy friend has been way too nice and has even let her sleep in his bed when he had texted her saying he was going to sleep. And then he gets a text saying, me too so why not I come over. Of course he should have told her no. But instead she comes over and she sleeps in his bed with him. Because he is not blatantly telling her he does not find her attractive he will continue to have this issue with her. And she may even get a little psychotic. I met her once and she just had to tell me that she was going to get him and for me to back off. I looked at her like she was insane. I had already been with this guy and we are friends and I have no interest in ever going there with him. But for her to have to feel she needed to tell me this was just asinine!
My friend that is a girl has an issue with a guy who has admitted he is in love with her. And she has told him many times that she only likes him as a friend. Whenever she hangs out with him, I have told her you are playing with fire. When people are in love they can not distinguish between friends and lovers. So if she was with another guy he did everything he could to sabotage it. Which he did a pretty good job of doing it to two people she was interested in. My thinking is she needs to cut the friendship off, because he will never be able to just be friends with her.
So with five stage clingers the best possible solution is to cut them off! Because unfortunately for these types of people they don't care if they get rejected over and over. They will continue to pursue you, because they feel entitled because their feelings are involved. Hopefully some of these types will realize not everyone is going to like you as more than a friend and trying to push that on someone is unhealthy and why would you want to be with someone who is only doing it because they don't want to hurt you?