Darren,
I think a lot of it is to do with people wanting to make a quick buck.
A woman around the corner from me buys stuff off ebay, then puts it up again for sale straight away at a much higher price.
Unlike someone like myself, who wants to use the equipment, and give it a good home.
That is how you get a seller with a load of bras and pants for sale, also selling the odd item of technical stuff.
Before I buy anything, I always look to see what else they are offering. If it ain't technically orientated, they know nothing about what they have, so it could be any old junk, and I avoid them like the plague, unless of course there is a very good photo and description, and you can see it is OK, then you can get yourself a bargain because again, they know not what they have.
So it is definitely buyer beware.
John