It's dominated by tourism. Having visited Moab, I would be surprised if it weren't a pretty Democratic town, but the rest of the county, which consists of rural Mormons, votes basically unanimously Republican, so it evens out with a slight Republican tilt.
This sounds reasonable... but it's actually far more complex.
Moab voting districts, pop. 8677, 2008 vote Obama 1884, McCain 1762.
Remainder of county, pop. pop. 548, 2008 vote Obama 183, McCain 109. That looks like the total opposite of what you claimed... until you look at it in greater detail. There are just three precincts not in and around Moab, and two of them that cover the entire northern 60% of the county have about 100 inhabitants. They indeed vote R, one of them with 80% for McCain. The biggest non-Moab precinct is Castle Valley in the southeast of the county, and that's its most democratic (and no doubt totally touristy) precinct at 65% Obama.
But of the area above described as Moab, only one precinct of eight is wholly within city limits and one is entirely outside. There are two dense central precincts, all the rest extend outward (all the way to the western county line, though no one actually lives out there.) As it happens, the one of the dense central precincts that actually includes a bit of territory outside the city is an outlier at 62% Obama; I suppose this is the area you thought of as the touristy Democratic town. The others come in at 52% (2), 51%, 50% (2 incl. the other central one), and then 46% and 42%. The 46% precinct is actually wholly outside the city and is ribbon development along Route 191, starting on the southern county line, and the 42% is north of it along the route, more than half outside the city by territory. Still these are both actually among the smallest of the six "outer" Moab precincts.
It's a ex-mining-gone-touristy town whose founding, ancestral population happens to be wholly Mormon, and that has limited the D growth compared to what it might have been elsewhere. What you need to understand is not all the hippie leftie voters in other such enclaves are newcomers, the locals get the bug too. Indeed if there weren't a welcoming element to the local culture in the first place, these enclaves wouldn't spring up.
And while I was at it I also looked at San Juan.
As a broad breakup, Blanding precincts (again extending outward) 4307 people, 68% White and 25% Native, 1164 McCain, 254 Obama. (Navajos in offrez border towns tend to vote much more Republican than on the rez if they vote at all, which they don't really tend to do. Same pattern is observable in Farmington, Page, Winslow...)
Monticello and wholly rural offrez precincts, 3820 people, 85% White and just 3% Native, McCain 1052, Obama 292, so actually marginally less lopsided.
Reservation precincts, 6619 people, 92% Native and 5% White, Obama 1776, McCain 370. Now
this is a polarized county that evens out to a slight R lean.
