Chuck some turps on your hands, feels oily, right? It was the water that cleaned your brake, not the turps. For the booster - there are so many other factors though, setup being a major one. The sound also can make you think your brake is working better when in fact it isn't. It's completely obvious that your brake will have more lock with a booster on... since there is more force going through the pads and into the rim! If it's an Evo setup then the 'booster' still helps a bit.