Tippy, you've brought up something I have also noticed in several ads (not that I noticed in this ad, I probably didn't look as closely as i could have as i never saw the size either).

That is, that some sellers seem to write 'worn only once' or something like that, when they look to have been worn numerous times.

I don't mind someone saying they have been worn lightly or that an item is still in excellent condition (if it is), but it is extremely annoying to receive shoes which are listed as worn once and find eg the soles well worn and pitted-which is what happened to me once and I wrote in the (positive)feedback that I would have preferred honesty.

As far as the boots in the ad go, I'd say a seller is safer to just list what size is actually written on a boot or shoe.  Less likely to get into trouble that way and avoiding headaches is the name of the game.