Seven classes of "weirdo" identified A study of so-called "customer service sabotage" found there are certain groups of people with the frustrating ability to spoil any shopping trip, flight or restaurant meal regardless of how enjoyable it ought to be. In a list that resembles the cast of Snow White and the Seven Dwarfs, researchers said that problematic customers fall into seven categories: dopey, grumpy, smelly, pushy, stubborn, inconsiderate and rude. People with these qualities, collectively described as "weirdos," are dreaded by waiters and hostesses because there is little they can do to prevent them ruining other customers' experience. The research was carried out by Joel Anaya, a Hospitality Business Management student from Washington State University. He studied more than 200 accounts written by frustrated people on websites such as "dinnersfromhell.com" and "notalwaysright.com" and found complaints about other customers could be broken down into seven groups. The most common were people who swear loudly, followed by customers who become irate or complain at the slightest grievance and those who have poor personal hygiene. The list also included people who stubbornly insist on behaviour which puts other customers out - such as paying entirely in pennies at a shop counter while a queue forms behind - and people who break rules, for example by pushing to the front of a queue. It was rounded off by inconsiderate parents who fail to control their misbehaving children, and slow-witted customers who monopolise staff's time by asking a barrage of questions and keep others waiting. Mr Anaya said: "Customers don't just go to a restaurant to enjoy a burger. They go to have a good time, to enjoy the ambience of the establishment. If that's ever affected, if they ever leave liking your hamburger but saying they had a bad time, that's not a win for the restaurant.