I think the hoppes gets dirty, but I wouldn't call it contaminated. It's a solvent, can be used many times. I've never hit the point to where it's not useful as a solvent.
I used to let pistol barrels soak in it for several minutes, then flip to soak the other end.
I don't clean bores very often anymore. But I drop AR bolts in the jar, just the bolt, not the carrier lol.
Even if the hoppes gets dirty, most folks wipe parts down after anyways, so nothing will be harmed