I always report offenses, but, sometimes, I feel as though it's a futile effort.
Trolls do just come back on different accounts, like you mentioned.
But what really pisses me off is that some people get away with it. For instance, there are a few accounts which always make multiple, really vulgar and explicit posts and threads, which are all reported, but the mods don't do anything. neutral Even after months of reporting those posts and threads, that account still exists and keeps repeating those offenses.
And even if multiple people have reported someone for a violation or for harassment, oftentimes that person does not get banned. What I have heard is that some people are friends with mods, and that they get away with doing whatever they want, because they have immunity... Of course, that is just hearsay.
Some mods fuss over trivial matters and don't worry about significant ones. Some go around checking very harmless signature images to see if they're over the size limit, instead of dealing with scam reports; others try to punish you, even if you have had a good record of reporting violations, for jokingly posting in an obviously reportable "10k giveaway if you click my dragon eggs" sort of thing...
Scam reports often take a long time to be reviewed; if they are, sometimes all you get is "Due to the circumstance that there was not any critical loss, your case has been resolved," and you get nothing. Hack reports are often left unanswered.
And they do all of these things, when there are so many other people who have made their entire Gaian fortunes by offsite trading (I've come across some people who claim that they have done this and have never been caught) or by systematic hacking...