Government money will always come from taxes. The only thing to really argue about as to how it is obtained and where it comes from is the preferred tax structure. Personally, I wish our progressive income tax system would be scrapped in favor of the fair tax. I'm very much supportive of taxing people based on how much they consume from the economy (how much they take from the economy) rather than taxing them on income (a measure of their input to the economy). As you may surmise, I'm a huge fan of the Fair Tax proposal.
As to whether the "legitimate causes" are beneficial to the whole population or a select group, I've always favored goods that are truly public in nature. That is to say goods that have the characteristics of non-exhaustion and non-exclusion.
Ideally, those transferring the money (the ones that WE elect to do so) are trying to do the right thing. There will always be crooks, that's just a sad by product of living in a fallen world. However, there will always be good guys in the government too.
I favor a government funded as per the original intent of the Founders which by it's very design keeps the central government small. The Fair Tax is better than the communist plank progressive tax we have now, but it still allows the central government to remain large and intrusive. If you want to kill the beast and preserve yours and your family's freedom... starve the beast.
Regardless... nothing is going to change until the people decide they've had enough of the King George. The abuses by our central government make the grievances in the Declaration of Independence look like child's play. But Americans take it... they deserve the government they have.