This user has five answers posted that are all the same spam advertisement for some website. I have flagged their answers as spam, but is there anything else we can do to prevent this from happening?
I've removed the offending account. The best thing to do is flag. If a post gets enough flags it will automatically be removed. Otherwise, one of the moderators will respond to the flags within a short period. Thanks for letting us know.
Flagging is the only thing that can be done. Rest assured, the response to the flags is usually quick, so no serious damage can be done by such users.
I was thinking about the same problem, I usually flag as fast as possible, and I think other users do the same. So unless the spammer is seriously flooding the site with ads, I don't see any serious damage taken, otherwise maybe there should be some other mechanism to deal with it.