Unions (and Employee Associations) around the country for the most part do good things for the workers. As with most bureaucracies, as they get bigger they get less focused and more wasteful. Until such point that they need to just implode (much like all forms of Government, really).
My personal experience is that our pooled dues were put to good use when we hired an experienced arbitrator to stand for us in contract negotiations. We got way more than we could have without a hired gun, money well spent.
The replacement of full time employees with temp workers (without benefits) is a HUGE part of what is wrong in our country right now. It is happening all over in the name of cost savings. Great plan for the company and the execs at top, bad news for the worker bees.