Rescuing silver coins from scrap merchants?

There are lots of businesses that buy scrap silver from people and then melt it down. I've been reading the forum archives and I saw a few posts about folks going to those scrap merchants, buying the coins (paying the spot price for silver) and getting some rare coins that way.

Is that a common practice? Is it worth it? How often do you visit your local scrap silver businesses? Are all the coins silver, or were there fakes in the mix?

This situation reminds me of animals in pet shelters: if they're not adopted, eventually they'll be disposed of. It feels fundamentally wrong to let the coins be melted down - they're tangible history, never to be replaced or reproduced again. (Well, that, and there are probably great bargains there, too!) Setting aside the relatively common US silver coins, this seems like a great way to build an objectively valuable collection while also improving my coin karma.

So now and them I visit those scrap merchants (official shops) and do pay reasonable prices for silver oldies in VF/XF state with mnor circulation signs (as the 1947 Syrian silver serie).
One thing it's for sure, before they sell they buy and they're at least pretty sure that they bought silver. That implicates automaticly that the coins I buy there aren't fakes.

Recuing coins it's definately a good thing but to me also applies to the copper and bronze ones.

I don't actively scope out the metal melters due to budget constraints, but I'm in favour of whatever saves the coins from the melting pot. I'd love to go to a scrap dealer someday and just buy whatever they have. It's like a really awesome surprise bag with the major bonus of saving a lost coin.

A lot of those kind of guys are bottom feeders and I’ve found them to be rude and once you ask, they assume they have something valuable and then ask too much. But it’s worth it to go around and ask, because if you can find a guy that’s not like that, you can get some good stuff at bullion prices.
I got some good stuff once but the guy says nobody has brought him any foreign coins since then.