What should be mandatory in every professional published review-

I dislike the clickbait on Youtube--especially when a reviewer says "This could be my last _______ (speaker, amp, DAC etc...)  Then 3 months later, they're reviewing another item that replaced their last whatever.

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.

at this point it is safe to say that most reviews are flawed and not an undeniable reference for purchasing anything.  they are constrained from mentioning anything remotely detracting about the sound and in fact barely describe the sound character at all. they simply cannot bite the hand that feeds them. 

most of the text in a review has nothing to do with how it sounds.  they are mostly fluff that includes company history, the new technology and why it should sound better, room and system setup, and maybe a little about how it sounds playing often obscure music.  even if the peice receives an enthusiastic recommendation there is little to go on in terms of how it will complement the sound of your system or its overall sonic character.  

buy from a place that allows a good return window and listen before you buy if possible.  

I think most of us know what we can learn from specific reviewers and which we can ignore.  Often based on personal preferences, and reviewers system, such as some that test electronics with only speakers that essentially have little bass...they all have flaws and also things we can learn..,.reviews help me learn about gear, not tell me what to buy...