I was looking over an old book and it pointed out that things taste sour because they are acidic, and bitter because they are alkaline. Would this mean that a good/balanced shot would have the acidic and alkaline components neutralize each other, giving the resulting shot a pH of 7? If so, could testing the pH be used to dial in shots by newbies? Or am I just imagining crazy things

Coffee has a pH of about 5, meaning that it is acidic and not neutral. The acidity of coffee varies based on the origin of the coffee and roast level with lighter roasts having a higher acidity. Many, and probably most HBers, enjoy the acidity of coffee as it contributes greatly to the flavor profile. Coffee with low acidity is often described as "flat" or "lifeless" while coffee with acidity is described as "bright".

Even so, I don't think pH could be used very reliably to assess coffees for quality. There are a number of different compounds that contribute to the acidity of coffee. Some can be astringent or sour, while others that are more prized have a malic or fruity taste. Kenyans have more phosphoric acid than other coffees contributing to their unique very flavor profile. Some people however prefer low acid coffees, like Indonesians.

Ultimately it's all a matter of taste and the best measure is a well-developed palate. pH may be a useful measure for the water you use in your espresso machine, but I don' think would be a good diagnostic for coffee quality.

Thanks for clarifying that for me!

I think the Acid vs Base of the pH scale is different from the sour vs bitter of taste. While I know most coffee has a pH around 5.5 and is an acid, coffee is naturally bitter (caffeine taste).