Sales reps knowing the line up, & catalogs
I spoke to some sales reps that didn't know as much as could be learned from the circulars and signs on the sales floor. They seemed to know the mid-line models best (the "bread and butter" models) and basically what was on sale that week, and the Lady K too because it paid a handsome commission. Certainly not all were that dense --- When I bought my '86s, the salesman was excellent --- he had a 20-year plus tenure with Sears and he knew his machines, even discontinued models from years earlier. He could have sold me an 80-series if he tried, but he said "Son, this is fine for you", or something like that, when I bought my entry level 70.
Sears usually had 20+ machines active, and some would come and go for various promotional periods etc. It wouldn't surprise me if few knew the whole lineup at one given time except for somebody in the Marketing Dept.
As to the catalogs, they did not contain the whole line, rather just an excerpt from the current total of models. Some models never made it into a catalog, others were there one issue and gone the next but were available for several years, etc.
Sears did some tricky things with their selling practices. They always had several 70-series machines current at the same time, so one could always be on sale, which is what the majority of buyers looked at, but the different model and stock numbers on sale week to week got them around laws that govern sale prices vs. everyday retail. In reality the only difference from one machine to the next would be four vs. five water levels, or this model had a softener dispenser and that one didn't etc. Similar things were done with the 60 and 80 series lines.
It would be fascinating to speak to someone who worked for Sears marketing in the busy years of the BD and DD washers.