I have used pre shave oil and dont like it. If your beard is not well hydrated before you put it on, it will actually coat the whiskers with oil and prevent the water from softening and swelling the whiskers. I have used AOS water based and Proraso which is water based also, although I dont use a pre shave anymore(dont need it). It served its purpose for a while but now its just something that doesnt bring anything to the shave for me anyhow. The brush can definitely get fouled if you get alot on it. Im sure the lather will break it down though. And who needs slippery hands?