"If a consideration in employing someone at the ticket counter is that they have well-founded opinions or suggestions to offer on films, then, by way of their expert status, you've cause to believe them."
I'm disregarding it because it's observably not true.
People are employed at theatre ticket offices because they are teens who are willing to work nights and weekends for minimum wage, not because they're film experts.
Expecting a ticket booth employee to be Roger Ebert is about as reasonable as expecting a Radio Shack employee to be a qualified electrical engineer.
Their opinions as to what constitutes a good movie are almost certainly wildly at variance with my own.
That said, Yelp-type reviews aren't much better.
About the best you can do is find a professional movie or restaurant reviewer whose opinions match yours and go with that.