Some items are obviously used - but others are end of lines etc. You have to be careful and obviously pick and choose. Sometimes they will have a set of say Yankee candles where one has been burnt but the others are new. I have had some real bargains - brand new and sealed smashbox tsv's, Northern Nights brand new pillows, and bed sets.
You can tell the used stuff - as no one could re-package a duvet set the way it comes new also they will have lots of one item rather than one or two.
I did get one of the Lori Grener long mirror jewellery cabinets - which looked like new it still had the seals on it and the blue tape over the mirror bit. When I got it home it had a note tucked into it with a ladies name and address(!) explaining that she had ordered it for a present and the orginal was damaged so instead of waiting for this one which was the replacement to arrive she had ordered a second one so this was the orginal replacement which she just returned straight back. So whether you would describe that as second hand would be up to you. It was also a bargain at £40 instead of £120 off qvc!