First, everyone is right, you will find both negative and positive reviews for almost every restaurant. For every person that the restaurant is their absolute favorite, it is some else's least favorite. If you think you will enjoy a restaurant, you probably will. Go and have fun and stop looking for reviews.
If you must read them, try to use negative reviews as a learning experience.
1. Ask yourself what is it that made this meal so bad and would those same things bother me?
Many times I see people complaining about things that wouldn't bother me at all.
For instance, some people like that buffets usually serve both breakfast and lunch items as they switch over between the two meals. Others hate this. If you don't mind the combination, your late breakfast won't be ruined by the lack of breakfast foods and inclusion of lunch items. If you had your heart set on specific breakfast foods that are now missing from the buffet selection, it might ruin the meal for you.
Another example, are the restaurants that joke around with you, some can find the servers rude or become embarrassed by the antics, while others love that type of atmosphere and aren't offended or embarrassed at all.
2. Is there a pattern to the bad reviews?
If one lone person reports an issue, it was probably a fluke. Any restaurant, server, cook, etc can have a bad day. The chances of you encountering the same issue are small. If 50 people all report the exact same issue, there's a good chance you may as well. In that case, see point one. Will this issue really bother you?
3. Be realistic and realize people like to complain even when the issue is their own fault.
For instance, if everyone generally agrees that the food at the sci-fi drive in is mediocre, but the atmosphere is why you go. Don't go expecting a gourmet meal. It's like going to McDonalds and then complaining because they served you fast food. In addition, people will go to a burger restaurant and complain they don't serve seafood or steaks. People will complain there are children at a Disney restaurant. People will complain they can't get a table at a restaurant they didn't make an ADR for, or they will show up outside their window and be mad their table was given away. Be realistic about what you are getting, and you will be happier. Any time you put something up on a pedestal, you are just setting yourself up for it to fall off.