I think the biggest example would be commemorative edition guns. Many of them are just expensive, gaudy versions of something common, and they often are made in large enough numbers that everyone who thought they were special already has one. The AR market has shifted toward more 3-gun style rifles and ban-era guns with old features are worth a bit less, as are pre-ban guns in -most- states. Years ago I rarely heard negativity about different options for ARs as the options were limited compared to today. Now it has to be a Colt, but they are overgassed, so it has to be a middy setup, but some of those are picky about ammo, and this brand is junk but that one is overpriced, and really you should build your rifle for nine cents with these options, but those parts are crap soooo... Meanwhile years ago the conversation was all pre-64 this, Model 12 that, and before all that it was "check out the gorgeous wood on this Monte Carlo sporter stock I'm using on my cheap Mauser project, complete with cool white line inserts and curb feelers". As tastes and available options change, so goes the market and the overall conversation.