Vegancat posted a comment on one of the earlier entries which I strongly agree with. He said that a lot of people don't realise the problem is not with the cats but with the people. For example, when people complain about 'dirty' feeding, it's not the cats' fault that people are leaving food around. Rounding up the cats and killing them, without changing the mindset of the people is not going to help - new cats will just come in, and they will continue to leave food around and create a mess. If however,these feeders can be educated and change the way they feed, then the problem will solve itself.
Same thing with people feeding the cats upstairs, or people who let their home cats out, and the cat defecates outside someone's home. Removing the cat really won't work in this case if you trap all the community cats and kill them when the cat that may be causing the problem may be someone's pet! The defecation problem does not go away and the complainant is still angry.
People also get upset with the cats if they cauterwaul or fight, or if they breed prolifically. Again, this isn't something that the cats can do anything about - but if their human caregivers get them sterilised, then these problems will all stop. Why the cats for something over which they have no control? Removing them again, leads to the vacuum effect kicking in, and more new cats will come in again, leading to the same problems reoccuring.
We have to make a conscious decision to really try and solve the root of the problem, and stop taking away the consequences later. This is akin to say treating the symptoms of an illness without going to the underlying cause of the illness itself. It will just keep recurring if the cause is not removed.