Well, I'm definitely sour as I've have had bad and really bad experiences with people my entire life. There have only been a handful of good experiences even though I have helped many people.
IMO. Most people are very selfish. Most people generally believe they are nice. They also believe most others are nice as well. It makes their life happier for them. However, after witnessing many "nice" people doing horrible things I wondered why this happens. I research things that don't make sense to me and then run experiments on them.
So, I started experimenting with "nice" people. I discovered that when people are in good situations they are generally nice. However, if their situation is not good then their actions are not good as well. People typically only do good things if it benefits them.
Before you say that's BS. So and so did this or these people are doing that, realize that they are helping themselves too. It can just be feeling like a hero. But it's still a reward. The only way to see how someone's true character is, is to test them where is it nearly impossible for them to receive some kind of reward. I.E. Continue to help someone that they do not like or think is not worthy of their help while costing them time, effort, and / or money.
For instance, I helped this person move and clean up their house so they could sell it. This person was a hoarder. It was a huge job. I was doing it out of years of friendship with him not to receive any other rewards. He kept giving me some of his junk as rewards. I said no thank you. I don't want or need that stuff. But he insisted. So, I took the items and tossed them in the trash when I got home.
Anyway, after a couple weeks only a few large items remained. He said he had no room for them and was going to haul them to the dump before he headed out of town unless I wanted them. It turns out that I really wanted two of the items. So, I told him I would really appreciate if he could drop them off at my place as he left town for the last time. He said great! We loaded up the remaining stuff in his trailer and setup up a time for the next day. But, he completely blew me off. I never heard from him again ever.
I found out that he made his trip just fine. So, I have to assume that he took the easier route and dropped the stuff off at the dump instead of also making a short trip to my place in order to make it easier for himself. After all, I was finished helping him. So, he would get no more gain to drop the stuff off at my place. But, it would cost him effort and time. That's just one example.