I doubt that we can eliminate the ESL askers altogether, and I don't think that we need to. Instead, I think that this should be approached the same way as "homework" on SO: via tagging. I propose [learning] specifically for questions intended for language learners, whether first or second language. E.g., both of the following could be tagged [learning] (and I'll probably retag them after this):
http://english.stackexchange.com/questions/421/how-can-i-learn-to-use-more-idiomshttps://english.stackexchange.com/questions/421/how-can-i-learn-to-use-more-idioms http://english.stackexchange.com/questions/384/how-does-one-know-when-to-use-a-gerund-or-a-infinitiveHow does one know when to use a gerund or an infinitive? http://english.stackexchange.com/questions/294/recommendations-for-non-native-english-speaking-bloggersRecommendations for non-native English speaking bloggers
This despite the fact that only one of those is actually from a non-native speaker.