Thanks guys.
I was asking because I was thinking about an inexpensive product that might be useful...but I think I'd be the only one to use it!
I'm not a card/wire brush man myself. I'm right handed, so after a few passes, I very easily-quickly-fluidly wipe the file hard on my right pant-leg. I'm usually wearing old denim or workpants (and have glue, paint, styrene dust and various all over them!). It's just so easy and fast because you barely alter the stroke/flow...file-file-file-wipe...while still holding file, and one handed, no need to grab a card/brush.
But the downside is I destroy pants. They're workpants, but often would have much more life if I didn't grind through the cloth on the right top thigh!