I guess my criticism went slightly over the top. Indeed, "use your brain" is not an insult if you say that to people you know pretty well, especially if they j

I guess my criticism went slightly over the top. Indeed, "use your brain" is not an insult if you say that to people you know pretty well, especially if they just did something extremely stupid that was easily avoidable. However, I still find it inappropriate to say that to strangers on the internet which you don't know. Of course you can try to extract a lot of character information out of a single sentence that somebody said, but the error rate is quite high.