I can relate to your disappointment.
I'm not sure how to deal with the one-on-one trade. I definitely would not deal with that entity again - But the rest of us would also like to avoid trading with that entity.
If you were doing I Spy type squares, some fabrics really should be fussy cut to get the maximum picture value from the fabrics. I realize that it takes more fabric that way.
So the question is - and there is no way to know the answer - did the sender really not know any better - or was the sender knowingly sending - what's a nice word for "crap"
If I understand the group swap guidelines correctly, they basically say if one gets disappointing things back in a swap, "It's put up and shut up"
But it seems reasonable to me to expect that if the swap says blue and yellow, to get back blue and yellow, not blue and pink.
It also seems reasonable that if the guidelines say 12.5 unfinished, that it be somewhere in the vicinity - not more than 1/4 inch one way or another. (My personal standard is plus or minus 1/8 inch)
I have come to expect some of what I consider "duds" in the charm swaps. I think some of the swappers just cut the fabrics with absolutely no awareness of what the individual squares look like. Whether this is due to frugality (cheapness) or inexperience is hard to determine from this end.
I won't even use some of them for a charity quilt - especially for a kid. If a kid needs a charity quilt, I think that kid should have at least one thing that's nice in his/her life.
Off my soap box.