Miller, sorry for the late reply - after a few days of nobody answering this one, I just stopped checking! Anyway, as an example, take a look at the PRO-T below - nice glove, it's just that the welting is a little dirty. Nothing against its owner - that's just how it is when you use a glove on the field, and there doesn't seem like there's anything you can do to prevent it.
If you try and clean it, some of the dirt from the shell inevitably gets onto the welting, and the welting itself doesn't seem to respond well to cleaners. It's more of a suede-like finish (if it isn't in fact suede), so that might compound the problem.