Well, that's just awful, and I feel your frustration.
In the past year, I have "standing offers" to fish in 4 different ponds. I have fished in exactly 1, because the guy needed some excess fish taken out.
I've been thinking about letting certain trusted people go fishing, but your experience (and already knowing human nature) has made me re-think that. I don't think I will ever invite anyone to go unless I go with them. Sad, isn't it?