If your dress rehearsal sucks, then your show will be good. But if your dress rehearsal is amazing, then your show is going to suck.
Sydney participated in musical theater in high school and was exposed to a plethora of superstitions on having a good show. She learned this specific superstition while preparing for one of her shows. Although she does not remember hearing this superstition from any specific person, she said that multiple people probably spoke to her of it. Sydney said that people do not necessarily emphasize this superstition (ie: they do not say it in class), but they do begin to mention it often as time draws closer to the opening nights of the show.
Only people in theater tend to know about this superstition. Sydney told me that it is commonly used after a particularly terrible dress rehearsal. People are scared of performing poorly. She says that another context she hears this superstition is after the first run of the show (ie: opening night). Someone would be talking to the director and telling them what a great show they put on, to which the director would respond with comments about how nervous he/she felt after seeing the poor performance at the dress rehearsal, but that it all turned out okay in the end. Then the superstition would be dropped into the conversation, making it known that a bad dress rehearsal usually means a good show. If the dress rehearsal had gone well, then it would be cause for more worry.
Sydney made comments on how the superstition probably had some validity, though was not necessarily true. She said that when actors have a bad dress rehearsal, many of the kinks are found and able to be corrected. Thus, when actors make a lot of mistakes during dress rehearsal, they can fix things before the actual show. Sydney also noted that if the dress rehearsal is excellent, then there is less room for improvement. Many things end up going wrong during the show that were not anticipated because they were not caught during the dress rehearsal. With these reasons in mind, she says that there is probably a correlation between the two factors, but the statement as a whole is not necessarily true.
This superstition falls under the sign category, where people look for signs from the universe to predict a good or bad outcome. However, instead of looking at tealeaves or reading palms, participants in musical theater look to the dress rehearsal as a predictor of success. At first the superstition seems illogical. If the dress rehearsal runs smoothly, then the show should also follow suit. However, I think that this superstition works by quelling the fears of the participants. Although Sydney had a more logical way of approaching the superstition, she said that many of her peers looked to the dress rehearsal as a concrete indicator of the shows success. I think that people have a need to attribute their fears and anxiety. If the dress rehearsal goes poorly, the saying becomes a way of coping with the additional pressure added to making a good show. It downplays the feelings of tension by writing them off with illogical reasoning.
This superstition also seems to work like a jinx, where it is almost bad luck to have the play turn out well before the actual opening night. It runs parallel to many other theater superstitions. For example, people do not wish good luck to participants for fear of jinxing them. Instead, people would rather hear break a leg. The opposite result of what is desired is spoken or acted in order to avoid negative results.