Sure, I could make it difficult to make money off of all this trash, but if i'm being realistic and i'm populating these dungeons full of stuff, and the only thing to be doing in the world is making money, I should be expecting this kind of behavior. They should be maximizing their income. That's one way to play D&D, but i find it rather tedious.Right. Players are generally wicked smart and will be devious as sin to get what they want. They want XP...if that XP is behind looted gold...they will focus being smart on getting that gold. Things like flooding dungeons by diverting rivers comes to mind. Smoking out monsters from their lairs. Playing monster factions against each other, then mopping up whoever remains. Coming up with wild heist plans to secure the gold with a minimum of fighting. That's infinitely more entertaining than "kick in the door, kill the monsters..."
Of course. But you don't let them.
What an odd juxtaposition. The DM's job is to keep the game from "devolving" into a video game. Letting the PCs have infinite, consequence free time to loot every scrap of tin or iron from a massive underground structure, and somehow haul an infinite load of stuff back to town, only to sell it all to the unquestioning merchants at retail...sounds like it's a video game.
Well, of course. That's why you don't treat it like that. Your job as the DM is to play the world as realistically (in a verisimilitude sense, not a simulation sense) as possible. Do you live anywhere near where meth is a problem? Addicts will break into places and steal every scrap of metal they can and sell it. Businesses have to put safeguards in place to prevent it and merchants have to prevent the addicts from selling the stolen metal. Same with regulations about pawn shops. Port that stuff into your XP for gold game and you'll see a dramatic drop off of nonsense.
I'm well aware that scrappers IRL will not just take random metal that looks like it was taken out of a vacant house. The larger point i'm making is that i find little interest in DMing the kind of fantasy that entirely consists of people looking for the next buck. If I was being realistic, the thing for players to do, being a bunch of well armed, trained people, would be to do a lot of crimes. I could of course make life difficult for criminals in response, but I prefer to be heavy-handed and just say that i'm not interested in running or playing that kind of game.
I do think counting money is an interesting way to put some pressure on a party- in a game where I have money and time really matter, I like to have PCs have a cost of living to maintain and expenses while they do their ultimate goals. Money is in this context a way to solve problems rather than the point- a minimum is needed, and much of their questing probably won't make very much. The random trinkets you could find spelunking aren't worth much monetarily, and i spell it out in session 0 so i don't have to play pawn stars with stuff like that. I have enemies, factions, etc working for their goals, and generally I give the players leeway in how they want to accomplish their goals, and try to reward intelligent solutions to problems.
I guess it's me, the evil railroady GM- my solution to players robbing apothecaries isn't to have them have some absurd security system or for them to be totally nonexistent- it's to just tell them what kind of campaign i'm running and to say no if their first reaction is to rob the hell out of the potion seller, and if they insist, to find a DM that's interested in DMing Grand Theft Fantasy.