Is it really that bad?

So I'm thinking about applying for a job at fast food places. I've worked in a grocery store as a cashier for 1 year and I've dealt with all kinds of customers before...I wasn't living the dream but it was tolerable. Is fast food really worse? I'm pretty sure I'd be just fine. I don't see why employees tell me otherwise. They act like they're in a prison or something. I'm sure its not awesome to work at Burger King but I need a job and quite frankly I don't let customers get to me that badly. It seems most of these workers are younger so I kind of figured they would put up S.O.S. signs and complain often. I was the same way when I got my first s***ty job as a cashier. But I'm thinking of applying anyways even if its just part-time. What do you guys think?