When do you quit contacting seller?

[Aroldo Villarreal]

I have collected leads on my CRM and have them scheduled to call back at certain intervals. For example, I have one that I know will need to sell eventually since they have a leak in the back which is basically running through the walls in the garage and out the front. It's a small leak, but a leak going on for months now. I know this because it's a vacant house next to my mother-in-law's and I have jumped the fence since I "accidentally" dropped my tree cutting tells over the fence while trimming my MIL's trees. 

Anyway, I have her contact info, called her and the daughter answered the first time and she said her mom would be interested in selling it. But never answered my calls again. Do I keep calling or do consider this lead dead?

Other leads are the ones that I made an offer and they said it was too low of an offer. These are vacant homes, which I pass by on my way to work and check to see if they have been sold, but they have not. Do I keep calling these guys even though they said it was too low of an offer? I CAN come up on my numbers, but I've heard many times just to stick with your numbers. If I come up it'll narrow my exit strategies, but still make a nice rental. 

Then I have the ones that, after showing them my offer and running through my numbers, they looked at me straight in the eye and said, "Get the F*** out of my house before I punch you in your f******* face." I'm assuming this kind of lead is DEAD right? Unless I am the one who ends up dead. But in my defense, the numbers made sense to me.