Tria Taproom, Philadelphia Twitter/@TriaPhilly

The pub at the end of my block has a lot going for it. It boasts a huge variety of craft beers, a beautiful patio, and a killer Monday night trivia.

But every time I order a fancy brew at a great bar like this, I wonder, is their glassware clean?

Luckily, there's a super easy way to tell. If the inside of your pint glass is dirty, one main thing will happen: Streams of bubbles will flow from the walls of your glass.

I know, it sounds weird because — unless your beer is flat — there are going to be bubbles dancing all over the place. But if the fizz is originating from the inside walls, your cup likely has some gunk in it.

Here's why: The tiny layers of grime are creating rough spots on the glass that agitate the beer. These are called "nucleation points," which provide a place for the dissolved gas in your beer — usually carbon dioxide — to grab onto and promote bubble formation. This makes your beer fizzy.

The physical process is similar to what happens when you drop a Mentos tablet into a can of Diet Coke. The dissolved gas in the soda gives the drink its bubbles. The liquid is bottled under pressure to keep the bubbles in, and when you open the can or bottle, those bubbles start to make their way out of the liquid, creating the beer's distinctive fizz.

While the gas will create bubbles naturally, this process can be sped along by giving the bubbles something to latch on to. An object with rough ridges or a bumpy surface — the Mentos, for example, or grime on a glass — can catalyze bubble-making.

In the classic Mentos and Diet Coke experiment, the mint drops into the soda and forms so many bubbles that it creates intense pressure. Those bubbles have nowhere to go but up, causing an eruption.

Nucleation is generally a good thing when it comes to beers. More and more, brewers and glass manufacturers designing glasses with lasered etchings onto the bottom of the cup to agitate the beer and promote fizziness and a frothy head.

But if this fizziness is coming from a dirty glass, then you should definitely bring it back and demand a new one. There's no shame in becoming even more of a beer snob than you already are.