I work for an elementary school teacher, with 1st-2nd grade Spanish-speakers. She and I get along. We avoid arguing over using a word like troca (what's said on the streets) instead of camión (what's in the Spanish dictionary). She admonishes the kids' usage of "Spanglish". I try to make sure they know which word is which and how to spell both.
On the streets they gotta know many words, 'cause they gotta be able to communicate. When somebody yells, "Troca!" they gotta know that means they're about to get run over, otherwise they're removed from the gene pool. They need to know "Camión!" at least for the same reason.
That's what languages are for--communicating. Since they live where 3 are spoken (SpaniSh, English and SpangliCh), they better know all 3, for the reason noted. Later when they get older, they better know the word chida means some vato likes them, or else he may never ask them out on a date. Another possible end to their contributing to the gene pool.
I encourage the kids to use camión rather than troca in their formal, literary writing. I'd rather they became a Gabriel García Marquez instead of like me, although I'm not that bad.
Obviously in my opinion, using what's linguistically called "vulgar" ("vernacular") language isn't vulgar ("morally crude"), per se. It's just valuable as a method of communicating the message you want to convey.
Out on the playground, trying to correct kid's speech to conform to the Spanish dictionary can be as successful as trying to get English-speaking kids to use the word "great" instead of "sweet".
Whatever side you stand on regarding this question, I propose one more to argue over: it should be called SpangliCh, with a "ch" sound, rather than SpangliSh, with the "sh". Why?
Let's face it--Spanglish is their word. Not ours, us SpangliCh-speakers. It's the term of the educated, the linguists, those who guard the sanctity of tongues. Statically, I say. If you're among such educated, you'll maybe not want to check a site like:
http://chronicle.com/free/v47/i07/07b00701.htm where the author discusses at length the existence of "Spanglish". (Site not endorsed by this writer, necessarily.)
On the streets, where what they call "SpangliSh" is used, I don't hear that, I hear "SpangliCh". There's some linguistic explanation of how Spanish speakers learning English acquire this habit, but it's been so long for me, I don't remember the reason. I just know it happens, and that's how it's pronounced.
Although the educated might feel we vulgarists should not be allowed to even name our own vulgar tongue, I say fokk 'em. It's our vernacular, it's our way of communicating. Can't they at least call it the same thing we call it?
In return, I'll call you Hispanic, individually, to your face (including via Internet) and not Chicano, if that's what you want. So, for instance I'd say, "You Hispanos sure got mucho money to buy such a chida troca." If this sounds fair, then gracias for your understanding.
(The effect of my suggestion on the gene pool is debatable as well.)