I recently purchased a Morrow Audio MA4 XLR cable and emailed Mike Morrow with some “critiques” along the same lines as the OP mentions. They have chosen to take the approach of customer like “sales” and seemingly have a successful business using that model. The % improvements are just approximations with the intent of giving customers an idea for what to expect.
I think what made my head hurt the most is that the primary driver for price point appears to be the number of wire runs in the cables, yet my XLR has twice as many as the equivalent RCA but is the same price.
I do like the sound of the cable in my system and am happy to have gotten it 50% off of retail while recognizing that 25% off is probably closer to the going rate.