The Conservative Party shifted far to the right after a hostile take-over by the Reform-Alliance. There is no question that the Progressive Conservatives did not want to be taken over by the Reformers. When the Progressive Conservatives elected Peter MacKay to be the leader of the party, they made him promise in writing that he would not form an alliance. MacKay signed the agreement, but then immediately reneged on it. The vote to merge gave equal voice to Reformers and PCers, and since the Reform-Alliance party was stronger, they won easily. Now the remnants of the venerable old party is in tatters, led by the iron-fisted and ideological Stephen Harper.
It defies belief that such an important party could be perverted by the ambition of one man, and yet it happened - and it happened with very little fuss. A few prominent Tories left the party and there was a fair bit of grumbling, but most party members seem to have stuck by their brand, even it's really only the color of the signs that stayed the same.
On the Liberal side, there is a much more minor example of the arbitrary and personality-based nature of politics. Stephane Dion entered the leadership convention in fourth place (in terms of committed delegates). But because of a secret deal he made with another candidate, he won the leadership. As leader, he is farther to the left than recent leaders Martin and Chretien. I don't oppose this shift to the left, and Dion has involved the caucus very strongly in his policy formulation, but still - there's an arbitrary nature to this shift that doesn't seem quite right.
In the case of the hostile takeover of the Tories, it's difficult to see how it could be prevented. When there are powerful people who are as unscrupulous and crafty as Harper and MacKay, democracy will be trampled. Mulroney wasn't quite as unscrupulous, but his election to leader in 1983 was also marked by some dirty tricks. I hate to say it, but the Tories have a record of employing some pretty shady tactics. Unless the party decides to stop tolerating dirty dealing, they're vulnerable to corruption.
In the case of the Liberals, it seems we need to reform how we elect leaders. We should give up the delegate system and adopt "one member-one vote", as other parties do.
On the NDP side, sometimes I wish there was a little more growth in the party. Policy-wise, they stay pretty much the same, and sometimes their rhetoric sounds a little stale and obsolete.