It's not just the JWs but alot of "salesmen" are turning to the "recent immigrant" (read mostly mexican) market. My wife is from Costa Rica so she speaks spanish too of course. I used to sic her on the JWs, Mormons, MCI and whatever other salesmen came'a knockin or a'callin and she'd pretend she didn't understand english. It was great fun for a while but what happend was that they send a spanish speaker to call a few days later.
BenBob is right in that there's a rich market in these "recent arrivals". They spend money like water cause we just give it away via welfare, free emergency medical services etc. and they love religion 'cause it makes em feel wanted here and helps ease any potential faint feeling of guilt they might have that they are stealing from us. Which they are.