This is an idea that's been floating in my head for quite some time. What pushed it back to the forefront was the Godspell preview thread over at BroadwayWorld. One user wrote a particularly scathing review of the new Broadway production after its first preview performance. This is not a new phenomenon online. Remember the Spider-Man: Turn Off the Dark reviews and video footage of the big injury? What about the Women on the Verge of a Nervous Breakdown reviews that suggested it was--based on its first ever performance in front of an audience--the single worst show to ever appear on Broadway?
What raised the Godspell thread to a new level was the anger in the response to a show that so few people had seen. The user was told he hated theater, had no write as a paying customer to discuss theater, and should be ashamed of forming a negative opinion about theater. In a new line of arguments, this user was also attacked for having the audacity to comment on a show that involves improvisation like Godspell after the first preview performance.
And you know what? That whole thread is fine. I'd like to think that people who have not seen the production yet would give a little more respect to someone who wrote such a detailed review, but there's no guarantee of respect online. The initial reviewer was well within their theater going rights to not like the show. Since he is not a professional critic, I don't even have a problem with reviewing a show during the preview period. It's more of a word of mouth scenario than a formal review that will garner traffic anyway.
The Godspell thread is a microcosm of an odd situation when it comes to professional theater. Chances are if you are actively seeking out shows to see, you are a theater fan. That means that, deep down, you do like what happens on a stage. You want to enjoy yourself and you hope that the new production you are seeing will do that. But like anything in life, not everyone is going to like the same kind of theater. Some theater fans can't stand musicals*, while others view most revivals as a cheap cash-grab with no artistic purpose. So long as your opinion is an informed opinion, it seems valid to me.
What I'm getting at is this. If you are going to express your opinion about a production, do it. Don't apologize for your views. Don't back down because someone says "how dare you [x]." If you are confident enough to express an opinion, you're confident enough to stand by an opinion.
As for people criticizing other people for criticizing something they like, lighten up. It's just entertainment. If you disagree, explain why. There is no need to go for the personal attack when even the worst production will have many things to actually discuss. You are doing the production you feel the need to defend so vehemently no favors when you decide your only argument as arguing that others cannot have an argument.
Go ahead and talk about how much you hate Wicked or loved Baby, It's You. You're allowed to have an opinion. Just keep it civil and on message.
*and I'm sorry for them.