That example does not surprise me one little bit. My guess is that the owner of the lock is a first time builder, that (1) Did not know how to disassemble a lock for proper finishing. (2) Bought a bottle of browning solution and did not bother reading the instructions. (3) Was in a big hurry, because this gunbuilding thing took a lot longer, and was a lot harder than anticipated. (4) Rationalized,"well it don't matter cuz it is on the inside and nobody will ever see it. (5) Never heard of removing the lock for cleaning and did not know that lubrication at the right place is your friend.
Believe me, after building a couple hundred front loaders and occasionally getting them back for service, I have seen neglect in maintaining locks etc. that would make you cringe. Mark Elliot wrote an excellent three pages on shooting,care and maintaining traditional firearms that I copy and hand out with every gun sold. Even with Mark's excellent instructions I still see lock internals frozen with rust. We are lucky to be able to share information on this forum, some of these guys could care less to learn anything further than how to make the gun go bang and possibly hit what they are aiming at.