I guess I've bought a metric ton of figures, but I can easily tell if a figure has been taken out/displayed or if its NRFB. So many of the HT figs are totally covered in tightly taped plastic sleeves or bags over hands, feet, waist etc.
I guess someone could very carefully peel the tape, save the plastic sleeves/bags, and then replace them all when it's time to sell, but what's the point in doing so? A 2-3 year old HT figure that's been displayed isn't worth a whole lot less than a NRFB figure - in many cases, the sale prices are the same.
I had a vast collection of Kenner vintage stuff until recently, mostly sealed in package, so I'm more than aware of the MISB vs MIB and package condition (most of my stuff was C9.5, so I get it) etc, but I'm not sure 1/6 figures follow the same pattern for most people in terms of mint packaging. I get figs used all the time that have a few dings on the box and I really don't care - and I'm defintely someone who cared with much of the 3 3/4" stuff.
There was a youtube video I saw the other day and it was the first time I've ever seen someone displaying 1/6 figs with the artwork boxes right behind, whereas with Kenner and even many Hasbro SW pieces, the packaging is half the display - that's why a third of what hasbro releases is a mimicking of old kenner packaging.