My local Argos stores 'use to' open packages for people to check the contents, but this stopped, because some people assumed that they were receiving returns.
Argos have a very good question and answer section below most items for sale, plus reviews from customers, which can be very helpful.
If the item is faulty, then Argos have a first rate exchange or refund policy. Even for items not included in their 30 day policy.
I suspect the DSR doesn't apply, you collected from store. But I could be wrong.
One thing that I did find out, was a description error on a set of speakers, after I had made a purchase. Got a refund, but it became evident that any description errors could not be corrected, due to the early printing of the catalogues?.