The smocks come up for sale fairly regularly over the course of a year. Often they are in bad shape, but there are a good number in excellent condition. I have two with 4 pockets and one with 2 pockets. I have never seen a picture or a collector who has a 2 pocket version other than me, so I unknowingly stumbled upon something 15 years ago when I acquired it in trade!
BGS items are often demilled. The most common things for the 1950/60s jackets is to cut off the D ring and loop on the back side. Often times the buttons are cut off, which sucks because they are unique and very hard to find. The 1960/70s jackets very often have the same problems but also large cuts on the back and very often the arm pocket is also sliced off. For the parka it's the same.
The trousers they very often have all buttons missing. Not only does this suck because they hard to find, but there is something like... from memory... 28 buttons in total. That really makes it hard to get the trousers back into shape.