As for the colour popping up, it wouldn't be hard. A silver (or similar dilute) would have two copies of a recessive gene. So bred to a non-silver (non-dilute) the puppies would most likely have 1 copy recessive, 1 copy dominant (non-dilute). So the silver (dilute) gene could then be passed on recessively for several generations, assuming the carriers were not bred to another carrier. Breed two carriers together you will have 25% non-dilute, 50% carriers, 25% dilute. So if a breeder has one dog who produces a dilute it is clear that somewhere in there a carrier recessive gene has been passed on. If that breeder rebreeds that dog, or breeds a related dog, that gene might show up again (particularly if the breeding is done to the now-known carrier). The only way to weed out the carriers would be to DNA test for the dilute gene, or to remove any breeding pairs who produce a dilute puppy (both sire and dam). But because you wouldn't normally get that dilute who would remove a top breeding dog because of a recessive colour gene? It's pretty complicated really.
I've seen these kind of debates in horses. For example in Arabians there is SCIDS, which in it's active form is fatal. However carriers have no problems at all. Ideally all carriers should be removed from the breeding pool, but because it is so widespread in the breed (though not truly common) it is difficult to persuade people to weed it out. In fact there are concerns that some very important breeding lines might be wiped out if it were removed (fallacy in my opinion...). The theory is that as long as you never cross two carriers, it doesn't matter. There is a DNA test available now, but before you only found out about the positive status of a mare/stallion when a foal dropped dead of SCIDS (about 24 hours after birth).
Even more serious defects like HYPP (which is a dominant gene which has symptoms in both full (HH) and partial (Hh) presence). People still risk breeding Hh horses because they like the type, and they can still produce 50% clear foals when bred to a clear partner... At least Hh x Hh breedings tend to be frowned upon... mostly... as are HH breedings... Doesn't stop people though.