on one's political agenda, then no, I don't find any reason for concern that organisation's such as Fox News or Breitbart's Big Government website are constantly attacking ACORN.
What would be their agenda in doing so?
Well, President Obama was once a community organiser, meaning that an attack on ACORN could double as a covert attack on him. Whitewater served much the same purpose during the Clinton years. The case was proven to be utter poppycock years before Monica Lewinsky came to national attention, yet the case wasn't fully and finally settled until just before Clinton left office. In the meantime, it provided right-wingers with a handy target, constantly "reminding" folks that Arkansas was a deeply corrupt place (Not that it was much more so than any other place).
If anyone had revealed anything deeply corrupt about ACORN, sure, we'd be right out in front condemning them. As nothing has been revealed besides the fact that its a big organisation with lots of independent offices, i.e., some idiots are going to disgrace everybody else by acting stupidly, we can only conclude that the attacks on ACORN have nothing to do with any legitimate concerns and are meant in bad faith.