Never Trust A Politician - That's Rule 1. There might once have been a time when politicians were honest, noble creatures who laboured for the good of their constituents but that time has long passed, especially in the USA (with the legal bribery you refer to as "campaign contributions"). All politicians, with the possible exceptions of Dennis Kucinich and Ron Paul (who I think is batshit but at least honest), will lie to you. They will do so shamelessly, convincingly and whenever it is convienient. The only difference is what they lie about. Currently, Democrats tend to lie about personal matters like extramarital affairs while Republicans tend to lie about policy things like reasons for starting wars, torture and the economy. Note that this can change and often does.
When George W Bush lied, it was easy to tell: His lips moved. Dick Cheney didn't bother lying, he just said "What the fuck are you going to do about it?" and then shot people. Their entire administration lied to torture people, essentially because they wanted to; shred the Constitution, essentially because they wanted to; avoid responsibility, essentially because they could and invade Iraq, essentially for the loot. Obama will lie to you if he's not doing so already. His lies will probably be smaller because Democrats tend to lack the same bully-boy bravado.
Rule 2 - Democracy Is Wasted On The People. There's this wonderful idea among political scientists that voters calmly take stock of the party positions before rationally casting a vote for the candidate who most closely reflects their own views. It's complete horseshit. People, as a mass, are dumb, stupid, panicky, not very intelligent, distrustful of intelligence, spiteful, greedy and vicious. As proof, I present Prop 8. A ballot initiative that might as well have been subtitled "let's stick it to the queers" and yet, the whim of the mob made it law and the California Supreme Court, in a decision I think is legally dubious and morally repugnant, said they could vote away people's rights by simple majority.
I'm not a big believer in democracy. During the 2008 campaign, much hay was made of the "elitist" label. The charge being that an elitist thought they were better than you and they knew how to run your life better than you did. Now, firstly, that's a misuse of the term and secondly, they probably could run your life better than you do. A fifth of Americans believe the sun orbits the earth, most than half don't accept evolution, a frightening number think your Founders were all Christians intending to create a Christian nation, Fox News is "fair and balanced" and more people follow American Idol than the nightly news. This is a people too stupid to be governed. And I'm not suggesting the British are much better. If there is a difference at all, it's only of tiny degrees. The national IQ of any nation is the IQ of it's dumbest resident divided by the number of people in the country.
I actually am an elitist. I believe nations should be run by their best and brightest citizens (which, I hasten to add, doesn't include me), not simply by their most typical. Democracy is, when applied as literally as the California Supreme Court did, simply a more organised system of mob rule and the mob are too damn stupid to rule themselves. They want government services but don't want to pay taxes, they want to smoke dope but don't want gay people to get hitched, they think global warmings a hoax and evolution never happened. If the British public can be represented by a braces and bowler hat commuter, the USA can be represented by an armed soccer hooligan.
So, I don't believe in democracy. It's a bad, fundementally flawed system but, as Sir Winston said, it's the best one we've yet come up with. Actually, one that works, at least for a while, is benevolent dictatorship. But the problem with that is that the dictator eventually dies and his successor may turn out to be Caligula.