The world's largest retailer, Sears, Roebuck & Co., used false and deceptive advertising when it claimed that consumers didnt have to rinse or scrape dishes before putting them into Sears' dishwashers, a Federal Trade Commission administrative law judge ruled yesterday.

Judge Daniel H. Hanscom said Sears presented "grossly deficient" evidence to support its case that its dishwashers eliminated in all cases the need for prior scraping of dishes, pots and pans.

Judge Hanscom's order, which Sears said it will appeal to the full commission, would prohibit Sears from making such claims in the future, and require that is such claims are made for any major home appliances, they be based on "competent and reliable" tests.

In a statement released in Chicago yesterday, Sears said, "We strongly disagree with the hearing officer's order." The firm said the advertising in question "has not appeared since 1975,"but added, "we had test which we felt were adequate to substantiate the advertising."

Sears said it particularly objected "to the broad scope of the order which covered products not involved in the proceedings." Judge Hanscom's order said any appliance testing would have to be conducted in "an objective manner," by "persons with skill and expert knowledge in the field."

The judge found that it was unfair and deceptive for Sears to claim that items in the top rack of its dishwashers would get as clean as those in the bottom rack because, he said, there was no reasonable basic for that claim.

He also found that Sears' advertising references to an "extra-hot," final "Sani Wash" rinse in some Sears dishwashers, including the statement that the rinse was "especially nice" for baby bottles could give customers the mistaken impression that the Sears dishwashers would sterilize such items. Thus, he forbade any such representations in the future.

Specifically, Judge Hanscom found that the demonstrations Sears used to justify its dishwasher claims, which were allegedly certified by the Nationwide Consumer Testing Institute, were "close to preposterous as proof" of Sears' claims.

Sears dishwashers are marketed under the Kenmore and Lady Kenmore brand names, and are manufactured by Design and Manufacturing Corp., of Connorsville, Ind.