This is the problem as I see it. Scott US Specialized catalog is 1000 pages. They want to sell new catalogs every year for profit. But they cannot possibly review every stamp's price each year. So they do their best, which is really subpar for a publication that costs $100. My guess is they don't have significant compute (data lakes, AI, and analysis) in place to maintain this, and rather rely on a modicum of dealer input.
So their business interests are competing with their accuracy. They have a determined amount of updates they can handle per year, and try to handle the errata as it comes. If you read the descriptions of how they determine their prices, it's almost always dealers, that are more than likely sitting on the stock of the very entries in the catalog. So contributing editors and in general stamp vendors have a vested interest in NOT reducing the prices.
How can they possibly handle all the data points? My belief here is they need to remove a lot of pricing data. My belief is every stamp under $1 USD at this point should be consider de minimis. No price listing, just a dm. This should equate to a value ascribed to stocking, storage and or delivery. At the beginning of the catalog this should be detailed formulaically. This removes the nonsense bumping of mid 20th century commemorative stamps from $0.40 to $0.45. It's moot, and not helpful. When people look at a catalog they should not get the idea in their head if they have 10000 .40 cent value listed stamps they now have $4000 in stamp value. They have a de minimis valued quantity collection of stamps, probably worth AT or LESS than Face Value.
On the subject of higher priced stamps, auction houses play games. Much of the fees of auction are hidden under terms and conditions. So when a stamp sells for 50% of cat at auction hammer, a buyer is paying way more, as they have premiums, shipping, other fees, handling, and tax (the last which I don't agree with). The catalog is clear that the price is for the perfect specimen (or close). The auction house/dealers loves this model because they can sell an imperfect stamp, and it becomes marketing where they are seemingly providing discounted offerings below cat. $500 catalog, opening at $150. That should entice bidders up to at least $300, right? Then the fees. Then the buyers total all in is closer to $400. Now you are at 80% cat to take possession. If the catalog prices go down, then the perception in the well established marketplace of the last many years, is that so will opening prices. Now I don't think opening prices should go down, especially if they result in bidding and ultimately the hammer. I believe if you got at least one bidder, you have set the opening properly in a well attended auction.
But the fear is real, if cat prices drop 50% then people obviously expect openings to do so accordingly.
But this vested interest of auction houses AND dealers (who are really one in the same - aka a money making business enterprise) is that catalog prices stay or go up only.
On watchcount type sites you can view the historic sale prices. This, like historic SAN closed lot/sold searches gives you an idea on what things sell for. It's very hard to compare apples to apples as stamps of the same. What I will say is this:
Catalogs (and maybe there should be more competition in this space to take on Scott and be a better product), should represent the market price of the 80 grade stamp. Then the bulk of the people know what their stamp is really worth relatively, and the well heeled jumbo gem collectors can fight over how many times over that price they are willing to pay. Not the perfect stamp, and everything else seen as a reduction. This is why you rarely see stamps (except for truly hard to obtain rarities) spike past cat.
Lastly, in my latest area of collecting, modern US errors, we are at a serious point of discount against catalog, particularly historically. Quantities of stamps where under 50 specimens are available are dirt cheap relative to catalog. Weak demand is an understatement. a 1502a (black omitted in 2006 was catalog at $1350). I saw one last week at Kelleher sell for $325, with a catalog of $850. A dealer is listing one at $450 stating cat is $900 on eBay
. So 2 right there. 5 more unique sold in Feb 2021 (4 part of a block). Houston sold one in 2017. 3 others sold at Siegel. I have one. As things thin out and get stuck in collections, that rarity can become worth a lot more if any demand shows up. It hasn't yet, but it's been good for me as a collector swooping in and assembling quite a unique error collection.