Despite having an A level in physics (where much of the course is being told ideas and taking them as fact) I am still largely against the idea of dark matter... But purely because of the ideas that scientists base their ideas on.
If there's an imbalance, they seem to often blame that on nature, not their mathematics. A lot of people are looking to make a discovery for something they believe doesn't exist... Dark matter, certain sub-atomic particles, etc.
It's an interesting concept, and I watched a programme on it the other day, but I still think there is an easily explaination. Muphry's Law may come into play