They are on a JP server. JP servers have been pretty free of RMT crap. I noted one interesting thing from the OP, they say that their English speaking friends have confirmed the same thing happening to them. It seems to me that the RMT scum are widening out their attempts to get customers, but are still focusing on western players since Japanese players apparently have enough sense not to buy gil.
I agree. Short of browsing in text only with image, popup, pop under, java and script blocking literally blocking everything except plain text, you cannot fully prevent issues, and even then....