The fact that hispanic (or to be more precise, Mexican) majority towns are some of the poorest, most illiterate zip codes in America, and have levels of socioeconomic and cultural dysfunction similar to what we see in the black community (gang activity, teen mothers, etc) deflates this whole myth of them being "natural conservatives" and "Republicans who don't know it yet."
I can see Cuban-Americans as a natural Republican constituency, but not most Mexicans.
I will argue again, you miss the point.
It is not all or nothing.
While what you say is true, that fact has nothing to do with the large segment that do not live in the conditions you describe. If there is a Hispanic community, there are subcultures within that whole. There are those that are prosperous and upwardly mobile and they need to be courted to become Republicans.
A few voters here and a few voters there and pretty soon you have a landslide (if self righteous conservatives actually get up the initiative to go vote)