Not always Peter a few years back the lib dems got in, but most of them were as green as grass and hadn't a clue, they didn't last long. The problem is with most councillors is that they are generally going to favour their own patch, couple that with having little or no experience and knowledge in making decisions on projects they know next to nothing about.
Why aren't would be councilors giving a competency test and interview to see if they fit to stand before the nomination goes through from their party? I have sat on a number of committees over the years and one of the first things I have always pushed for is a skills audit of the board/committee to find the strengths and weaknesses of the group and see if training and or additional people should be sought with the appropriate skills. instead in a lot of cases we get a mish mash of people some with skills, some well meaning, but a lot who are about as useful as a glass eye in a blizzard.