Pericles, I agree with Pelican as to the forms donations to political parties take. Most donations, certainly all of the small ones, fall into the category of supporting policy or ideology, there is no problem with that just a part of a democratic society.
The dangerous donations are those that seek to influence policy and in the longer term law. The bet each way donations also may seek to do likewise, but the donor is making sure he backs a winner. By nature to influence, a donation has to be large, otherwise you defeat the purpose. This brings into question all large donations to political parties, be they from a corporation or an individual. However, simply because a donation is large does not exclude it from being for the good purpose of supporting policy or ideology. Then again a large donation could be for both a good and bad purpose, on one hand supporting policy and ideology and then on the other attempting to influence.
I believe on carful analyst the large private donation by Graeme Wood to The Greens passed the test for good donations and the money was put to proper use by the party. Senator Rhiannon expressed her concerns about the donation and rightly so, such donations must be treated with suspicion and carefully analysed at all times. As far as The Greens are concerned Rupert can keep his cheque book in his pocket. LOL