As for in game "harassment". I agree that it doesnt really do much, and I certainly wont bother to chase after scammers and yell out "scammer" after them.. thats just pointless to me. Scammers are frequently kos'd in PvP though, and for a good reason. Besides that, I dont see many ways of making their lives miserable other than what I've mentioned, which is only a fraction of the misery they've bestowed upon their victims.
I do that whenever I see Hikarih. Harrassment or not, I have a distaste for scammers (Like most people) and I won't waste a second to denounce them. It doesn't do any good, but it just satisfies me. Knowing that the people around her will think of her in a more suspicious tone. I know many people who do not know she is a scammer which makes me confused and mad =/
Not really informing, I guess it is harrassment