It is almost ancient history now, but the issuance of the 1989 Scott catalog almost caused the demise of stamp collecting. New editors of Scott felt that the traditional discount structure of our hobby needed to be changed, though this system had served the hobby well for decades. Then as now stamps sold at discounts from Scott value. High quality stamps from popular countries would sell at high percentages but off quality stamps, collections and unpopular material then (as now) would sell at substantial discounts. The Scott editors felt that the Scott catalog should be a true retail catalog and they slashed the catalog values between the 1988 and 1989 Scott, sometimes as much as 75%. 

Everyone except the editors of Scott had been comfortable with the previous pricing structure and knew how to buy and sell stamps based on the way the catalog had been for over a hundred years. As with most fixes for things that aren't broke, the "solution" was a dismal failure. Collectors were accustomed to buying stamps at a discount to catalog value and stopped buying as the percentage of Scott that stamps were being offered at increased. Demand evaporated, and collectors and dealers alike had to mark down enormous amounts of philatelic material. The market was damaged for several years and only really came back years later when Scott had raised its prices to the point that significant discounts were again possible. This was the first time that many of us learned the danger of well meaning reformers.