In response to Leonard Jacobs (responding to me):
A review is a critical, but still at heart opinionated, appraisal of a work as is. So long as the format of the production you saw is acknowledged -- i.e., during previews, with an understudy, &c. -- then I see no reason why *THAT* performance cannot be objectively (and comprehensibly) covered. That's like saying the beta version of a software shouldn't be reviewed: not so. Such appraisals (often called "previews" but really, simply semantics--i.e., what if I just add a small "p" to my "review"?) are useful to people wondering about the process, the show, the buzz, and more.
The Little Mermaid, currently in Colorado, is getting reviewed there, and read about by interested audiences here. (The production there is even acknowledged as a tryout, and isn't that the same as a preview? Again: semantics.) When it comes here, it will no doubt be different from Denver (Riedel hints, through much denial, that it may have a new director), but does that invalidate the right of critics over there to review what they saw? Or should New York City audiences (and all relevant tourists) be under embargo from reading those foreign reviews until after it opens here? Why can't I read about Spring Awakening playing at the Atlantic Theater or Rock 'n' Roll playing in London? Someone sinking that much money into a show -- even a preview of a show -- should stay willingly in the dark? And let's not ignore that publicists reviving a show use quotes about what's been said about earlier, potentially different versions. Ultimately, if you aren't ready to be reviewed, don't let ANYBODY see your show. Everybody's, as they say, a critic.
However, the argument here is about what you call the "separate but equal" critics... where's the equality? I seldom get scripts when I attend a show, I rarely get press material, and I only occasionally have a seat reserved. I am certainly treated differently from the mainstream, and most invites are from people who are curious about what I might say about the show, formal or otherwise.
There is a difference between blogging and reviewing. I made that clear in an earlier post. It has to do with the medium you release your material into, and whether it's an institution or not. Denton et. al. are free to post reviews on their blogs: if they post to their INSTITUTIONS (for instance, if I were to post to Theater Talk), that would cross the ethical line. It goes from a singular thought to a commercially backed opinion by dint of the editor's publishing it.
As for hurting the artists? I've gotten thanked by people during previews and cursed by people after openings. I don't really think they're the fragile creatures you make them out to be.