There's no craggy old man telling a story that makes zero sense…
… or making vaguely threatening predictions about the future, like some demonic soothsayer who might explode when exposed to open flame.
There's a Wi-Fi code
Conversely, if you ask the bartender, "What’s the Wi-Fi code?" and aren’t immediately told to leave, this might as well be the Ritz.
It's selling souvenir sweatshirts
A fake dive bar sells $40 hoodies with the joint's name on it. At a real dive bar, $40 will cover your tab for the next week, plus give you full access to whatever you want to take from the lost and found.
Nobody stares you down when you enter
The record scratch when you enter isn't necessary (and, let's be honest, the record player's been broken since '83). But what is necessary is that everybody in the joint immediately goes silent and leers at you. They're most likely going to tell you you're not allowed to sit in "Bill's seat" either, despite Bill not being anywhere to be found.
There's a top shelf
Whiskey is whiskey. Rum is rum. The only thing on the top shelf should be the urn containing Bill's ashes.