The fact that you get income from your photography is unimportant. I'm a pro too...meaning, I expect and strive for professional results. What you mean is you're a commercial photographer I suppose. We all want and expect the best in our photography.
Front element stuff often times has no effect on images, assuming there's a proper hood on the lens. I once had a Nikon 35 70 2.8 lens w/ deep and numerous scratches on the front and never saw any issues whatsoever. Some of the scratches were more like deep gouges, and I filled them in w/ black paint. Stuff on the rear can be an issue. More damning is haze or fungus. That's where you'll get flare and/or image degradation like a softening of the image.
The only times I'll use a filter is for B&W, and that's all I shoot. Everything goes into a darkroom, so there's no post processing of issues in software. I use yellow, orange, that sort of thing. One of my best shots was ruined by flare from a UV filter, and it was a Leica filter w/ a more than adequate hood. Anytime you screw a piece of glass on the front of a lens you risk flare.
Last edited by momus; 08-16-2013 at 04:11 PM. Click to view previous post history.