About one in five home sellers is dissatisfied with the assistance they received from their real estate agents, about double the typical disapproval rate for other service industries surveyed, according to an article in the July issue of Consumer Reports magazine.

The survey, the first study of real estate sales agents by Consumer Reports, found that about 20 percent of the readers, all of whom had sold a house in the last four years, described themselves as less than satisfied with the service they received. In contrast, in studying service rendered by other industries, such as auto and homeowners insurance firms, car rental companies and hotels, the publication said it has encountered a 10 percent disapproval rating.

In a survey conducted as part of the publication's 1989 annual questionnaire, about 20 percent of Consumer Reports readers who had sold their homes within the previous four years said they had switched agents while their property was up for sale, and about 75 percent complained that they had sold their homes for less than the listing prices. Nearly a third reported problems of one kind or another, with most saying they believed the agent did not earn his or her commission.

"... Surprisingly large numbers of sellers believe they do not get their money's worth for the thousands of dollars in commissions they pay for an agent's help," according to the magazine.

Spokesmen for the real estate industry countered that selling a home is such a disturbing and emotional experience for most people that a 20 percent disapproval rating is really a ringing endorsement.

"That says that 80 percent of people were satisfied with their transactions," said William D. North, executive vice president of the National Association of Realtors. "I'll take those odds to the race track any day."

North said it showed that many sellers are pleased with what transpired, particularly considering that real estate transactions are generally the product of negotiation, with both parties forced to make concessions to make the sale.

"It's a remarkable, remarkable vote of confidence for the real estate industry," North said. He added that sellers are unrealistic if they expect to get their listing price, which he said is really a sort of wish price.

The article in Consumer Reports acknowledged that the emotionalism of a home-sale transaction could cloud home sellers' perceptions.

"It's no great surprise that real estate agents seem to have more trouble pleasing consumers than do other service-providers," the article said. "They are, after all, one element of what is for most people a difficult and stressful experience. It starts with strangers trooping through your home looking for faults. Once a potential buyer does come forward, you must haggle over price -- and wonder if you got as much money out of the deal as you could have."

The survey found that the happiest home sellers were those whose homes sold within a month or were sold at the listing price. The unhappiest were those whose homes took up to two years to sell, who had to drop their prices by $25,000 to $50,000 or who eventually found the buyer themselves.

The survey asked Consumer Reports readers a series of questions related to their most recent home purchase and asked them to rate the real-estate agency they worked with. They received almost 72,000 responses, with more than 56,000 readers saying they had employed a real estate agent in the transaction.

The survey also found:

Nearly half the readers interviewed more than one agent before signing a listing agreement, but more than a third chose a relative, friend or neighbor to handle the transaction.

About 23 percent sold their homes at the listing price, 4 percent sold at a higher price, about 71 percent dropped their price by less than 25 percent, and only 2 percent dropped their price more than 25 percent to make the sale.

The average commission paid to an agent was 6 percent of the sales price, or an average of about $6,000. In the Northeast, the typical house sold for $142,000 in 1988, so the average commission was about $8,500.

Consumer Reports is a publication of the nonprofit Consumers Union, an organization created in 1936 to provide an impartial review of products and services available for sale to American consumers. It tests products, conducts research and issues reports on business practices and labeling questions. Its findings are published monthly in Consumer Reports magazine.