While heading the Business Desk at Indian Express Ahmedabad (this important post made many a CEO those days send their representative to contact me) I had a similar problem of my being good to others turning into a weakness to be exploited .
I went out of the way to help a young man who was into some attar (scent) manufacturing business when he had NOT sought my help.
He was a tenant living below my flat and one day my wife heard his wife talking to someone about bureaucratic red-tape causing problem to his start-up business. My wife had casually referred this to me and I foolishly felt enthusiastic as I thought I am in a position to help him. My wife was not happy and warned me not to be overenthusiastic as all she did was overhear someone while cleaning the area outside the door. “We know nothing about their antecedents” and therefore let it rest at that, she said. It was prophetic and sane warning which I ignored when I met this guy a few days later.
I offered to help which he gladly accepted. I went with him and solved the problem dogging him. After that there was no word of thanks or any contact with him. But when he vacated the house six months later there was no love lost in him. He behaved oddly against me as if I had harmed him in some way. I was too disgusted to ask him the reasons for his strange behaviour. He clearly seemed an ungrateful wretch.
MORAL OF THE STORY?
AVOID HELPING SOMEONE (especially the unknown chaps) WHO DO NOT SEEK OR CARE TO SEEK YOUR HELP.