I feel just the opposite [to a point]. I've had and used lenses with very light 'cleaning marks' on the front element and some with noticeable scratches, and even had a lens with a chip (filled in with black paint), they have basically no effect on optical quality. I also make a point of using a hood on my lenses for both protection and to shade the front element.
The rear element is something else, and would conceder a lens with marks or any kind damaged with rear or internal problems a compromise in optics.
Ideally I want a lens in perfect condition of course, but if cost is a factor sometimes you can get a real bargain and get a lens with light 'use' on the front that it will be just fine in practical use.
