the content itself is removed and replaced with a brief explanation as to why, which transgressions have been made for example.
Snas,
if you had an idea how many posts need deleting in this thread you wouldn't propose it! We have to make a living outside the moderating job, and this thread had us ask for help to other Mods because of all the wrong kind of excitement and extra work it causes. As for "explanation", all you need to know before hitting "Send" are mostly the website Rules that you signed when you joined, a little manners and a splash of common sense.
Also, we have as a rule not to interfere with a user's post itself other than deletion. So no adding or deleting stuff in the post. The full post either stays or goes.