It happens to the best of them. Prom dresses, video cameras and CDs are used and then returned to stores for refunds not because they're defective, but because consumers -- whether brazen or deceitful -- want to have the benefit of the items without being out-of-pocket. To discourage the growing practice retailers call "consumer opportunism," two UC Davis professors of marketing and another who is now a consultant recommend stores implement different return policies for different merchandise. Professor Eitan Gerstner and Associate Professor Michael Hagerty of the Graduate School of Management, along with consultant Scott Davis, surveyed 131 stores in the Sacramento area for their research, to be published in a forthcoming issue of the Journal of Economics and Business. They found a retailer is more likely to offer a low-hassle return policy when its products' benefits cannot be consumed in a short period of time; when its diverse product line allows it to sell other items to the consumer returning the merchandise; or when it can recover much of the value of the returned merchandise. Less than 10 percent of the stores offered an unconditional return policy, but none had a policy of "all sales final" for regularly stocked merchandise. "Product-specific policies may be what stores need to discourage consumers from abusing the privilege of returns," says Gerstner. "Retailers could implement tough policies for things from which the value can be easily extracted, such as party dresses and videotapes, and more flexible policies for items, like calendars, where there isn't a quick advantage to be stolen."