You won't escape them completely, especially on NA servers, but some servers are worse than others. Up until a few weeks ago, I would get maybe one spammer a night (not even one sometimes, maybe three nights a week), who would send two tells and then shut up. I wasn't even blacklisting anymore; the difference between blacklisting and not was literally one /tell. That had been the case for months, while reading threads from other servers where people would be blacklisting five or more spammers a day. In the last couple weeks, it's increased, and I now have 1-2 blacklist entries a night (because they no longer stop after two tells).

Japanese servers apparently have next to zero RMT spam. But with Japanese servers, you've got the language barrier and latency.

Blacklist tip: Clear it out regularly. Characters that are actually deleted show as (Deleted), but when an account gets banned, they don't bother deleting the characters, so those will still show in your blacklist, even though they can safely be removed after a couple of days.