I think the issue with the "Hispanics are 'conservative'" adage is.....well, hold on, there's a few issues.
First issue - a lot of this seems to be based off the notion that many Hispanics are Catholics. Which I believe numbers do back up in terms of it being the largest single religious denomination through that population. However, the issue is this natural assumption that ones personal social views correspond with one's political social views. Those within the traditional American culture hear about religion and politics and naturally tie them together in a fashion similar to what we see in the "evangelical" crowd. The notion of someone being "socially conservative" on a personal level for religious reasons, and yet not being strongly "socially conservative" on a political level is a bit of a confusing prospect.
But the reality is that for many of the Hispanics being talked about, you're speaking about a different culture than that found within the traditionally American religious culture. There's no reason to simply ASSUME that because most historically American groups heavily vested in religion tend to tie that in with their voting habits, that a different culture is going to feel the same way. Essentially, just because their religion is important to them does not inherently mean that their religion is going to guide what is most important to them in terms of VOTING.
And, even if they are largely social conservative, that may not override matters if they're fiscally or governmentally liberal.
Second issue - There is a realistic major issue that makes perfect sense for many Hispanic voters to view as a "single issue" type thing; immigration policy. And this can go both ways. On one hand, you can have some individuals who immigrated the right way and have distaste for those who are doing it wrong. HOWEVER, because ethnic communities tend to stick closely together during the first generation or two into a new country, the reality is that many likely know family, friends, or family of friends who have either had bad luck with our immigration laws or have circumvented them. As such, there's likely a large portion of the population, even those who did it the right way, that have a very keen interest and empathetic stance towards immigration laws.
Third issue - this stupid assumption that somehow a race steers an individuals voting habits. Age, social status, economic situation, geographical location, and more can all impact how someone's likely to vote. This stupid assumption of whole bloc voting is, to me, a bit ridiculous. The reality is that there may be other factors relating to the Hispanic population in this country that is actually the larger contextual reason for why they tend to vote more heavily democratic then simply their race or their culture.
To me, RACIAL demographics in and of themselves are a useful, but hardly singularly telling, population data point that the Republicans should be looking at. I'd say the socio-economic scale would be as important, if not more so, for them to look at.
For instance, if Republicans tend to do very poorly when it comes to those in "poor" classes, it's a coin flip often within the "middle class", and they tend to win with the "upper" classes.
So one can ASSUME that everyone votes based on what their skin pigment is, but what if that's not the case? What if in reality, it's more about class. By a quick look at the numbers, it seems there's significantly more Hispanics in the poorer or lower middle classes. What if over the next 10 years that shift though; that we have an influx of Hispanics, but more of them begin to enter into the high portions of the middle class and into the upper classes? The "race" numbers would suggest Republicans would have a hard time with them, but economic numbers would suggest that'd be a boon for the Republicans.
The reality is there are a number of factors that people vote based on, and such heavy focus on some of them that people on both sides do I think misses the bigger picture.