In part, I suspect this was fuelled by last night's feel good opportunities: the Boy Wonder was playing at a venue in London which was only accessible by a road which had been blocked off due to roadworks. It became clear that prior to the roadworks it was possible to get through to somewhere else, so after watching a couple of people walk all the way down and then turn back when they realised they couldn't get through I started helpfully pointing out to people that they couldn't get anywhere. They were all grateful for the knowledge which allowed them to save a few seconds and not look like a pillock and I felt like a good Samaritan for helping them out. It didn't really matter that the time it took me to explain to them was around the same length of time it took most people to work it out for themselves, because instead of a neutral observer, I was a helpful contributor which I found satisfying.
Presumably most people who are motivated to help others gain at least some gratification from doing so, in which case can they really be considered truly altruistic acts? Is it still even vaguely altruistic if you start to feel vaguely resentful to people who turn out not to need your help when you were already prepared for the feeling of doing a good thing? I'm pretty sure that I'm not a terrible person, even that I am more helpful than most, but is it really appropriate to begin to have secretly resentful feelings for a girl who just left her cardy on a sofa when she went to get a drink?