I do tend to use those in exactly that way, yes. However, while your mileage may vary, I end up getting the same complaint from the users either way. Even when

I do tend to use those in exactly that way, yes. However, while your mileage may vary, I end up getting the same complaint from the users either way. Even when my 400 contains an exact reason why the input is incorrect. Granted, on the one hand, this can be fixed on the individual level, but on the other hand, it's the same effect writ small that when writ large makes the response codes nearly useless, so this post is maybe half cathartic grousing. I can't push caring about response codes. I can document it, I can yield detailed errors, and I can be as careful as I like, but this is a "it takes two to tango" situation and at scale, on average, the other end doesn't want to tango.