The original “Texas Chainsaw Massacre” was admittedly kind of scary, as were the original “The Exorsist” and “The Omen.”

But the shock factor in all three franchises has worn off by now. Yet, because teenagers can still sneak into R-rated movies, sequel after sequel — and prequel in this case — will continue because producers know they’ll make money. The fact is there has never been a decent sequel to a horror movie, and “The Texas Chainsaw Massacre: The Beginning” is no different.

First of all, as a prequel, the concept inherently has a problem because you can assume that if anyone had survived the prequel, chances are they would have notified authorities of a cannibalistic family roaming the countryside. Therefore, there would be no possibility for the original. But since the original did occur, as did its three sequels, we can assume there aren’t going to be a whole lot of survivors. And as a result, we don’t have to care about any of these ridiculous characters.

Secondly, Michael Bay was the executive producer on this film. Any moviegoer knows that as soon as you see his name in the credits, you might as well have checked your brain at the theater door because there will be no use for it during this movie. Just look at some of his past films: “Armageddon,” “The Rock,” “Bad Boys,” “Pearl Harbor,” “The Island” and “Playboy Video Centerfold: Kerri Kendall.”

The film stars Jordan Brewster as Chrissie, the most logical of the group — and “logical” is a very relative term here. Her boyfriend Eric is a Vietnam vet trying to convince his little brother Dean to join the service. Dean’s girlfriend Bailey (Diora Baird) is persuading him not to go. The foursome is heading cross-country when they get into an accident and meet the local cannibalistic sheriff, played by R. Lee Ermey. The sheriff takes his hostages/supper back to his house and that’s where the fun begins.

Give the writers credit for making Eric a vet because it allows for him to do nonsensical things — like wading in dirty murky green water spying on people while in his backyard pool — and get away with it. After all, he probably suffers from post-traumatic stress disorder.

Also, commend director Jonathan Liebesman for his classy and artistic choice of conveniently setting up the camera directly behind Brewster as she crawls around the house on her hands and knees in low rise jeans.

For those who care, the movie answers some pressing questions like why the chainsaw is the weapon of choice, and where Leatherface got his face — it’s not made of leather in the traditional sense. Other than that, there’s no reason to see this waste of time.