What should be mandatory in every professional published review-

Nope, there isn't. And trust me....I read and think about this stuff WAY too much. You simply won't ACTUALLY know the sound of a thing unless you give a component time in your system...If a lot of reviewers say the same thing about something you can make reasonable assumptions, but that isn't actual "calibration," it's just allowing logical influence...I bought a Pass XA-25 after countless positive reviews knowing full well it would compete with a treasured and amazing sounding tube amp I already owned, and it did...lucky me as I didn't have to send it back. I think speaker systems are likely the most risky, and I've proven that to myself too many times.

A few other things should be mandatory: What does the item smell like? How many total parts does it have? Can it survive being attacked by gorillas? Does the warranty cover excessive rust? How long can it float? Can its lights lights trigger a seizure? Can you sit on it? What temperature does it reach when disconnected?   Without these things being addressed you just can't take a review seriously.

Many reviewers post all of their own gear...would a photo make it sound better somehow? Because in either case you ain't gonna hear it.

Note that reviewers live in a world of allegedly quantifiable differences as they have access to myriad items that the great unwashed do not. That said, and having said that, your and my ears hear different things and I for one have proven to myself the value of my tastes over all, as I tend to use my own earballs to make audio decisions. Example: New Klipsch Heresy IV...bought a pair and decided that although they are somewhat better built than the IIIs I already had (better speaker mounting screws and binding posts, ports lowering the bass frequencies by 10hz or so, AQ wiring), the IVs redesigned mid horn (simplified poly drivers replacing titanium full throated drivers) had a high-mid frequency bump that sort of yelled out. I couldn't stand it so I sold 'em and am happy with my lovely IIIs. I also sent back some well regarded Sonists, and a pair of pretty ZU Omens that were sort of awful. How anybody likes Dirty Weekend speakers is a mystery, but I don't really care, and hey...what do I know anyway? All well regarded with great reviews, but until you have them in your listening space you simply don't know. For me the reviews should be well written and entertaining, with expected grains of salt available in any readers head.

There is no way to "calibrate" your hearing...you simply have to hear things yourself as (previously stated I thought) generally you not only haven't heard the item being reviewed at length in your system, you likely haven't heard any of whatever the other compared items are, again, at length in your system. What was that quote?, "Writing about music is like dancing about architecture." Maybe from Martin Mull...in any case, again, if the writer is interesting I feel lucky, but there is no proof unless I can get my hands on the pudding.

El redundo los bloviato a mundo.