I just came across a spam answer which is extremely vulgar (sexual). I flagged it for moderator attention, and then it occurred to me that I could edit it and erase its contents by blanking it till a moderator gets to look at it. Is this an acceptable thing to do?
Rude/abuse/spam deletions are causing -100 rep loss to the OP and the post content is defaced. People having access to the deleted content (OP + mods + 10k+ users) can still see it, but even they need an extra click to see its edit history.
These deletions can be caused by at least 6 spam/rude/abusive flags, and possibly also by mod. The deletion will happen as if it had been done by the community bot. Mods get notified and they decide, what to do to the perpetrator. The most likely consequence is either suspension, or account destruction (if it is a low-rep spammer).
Defacing the post would remove evidence. Vote down, flag and wait. If you get back your lost rep, you know that it is done. Normally it happens quickly.