The only way I know of is to use Google Earth's Street View. Drag the little man icon onto the road you're interested in and see if it looks to be paved. Unfortunately, just because one area looks to be paved, of course that doesn't mean the entire road is
Yep, what he ↑ said. If the road doesn't highlight in blue when you bring the little man icon near it then 90% chance it's not paved. Get the street view at the ends of the road in question and inspect from the paved ends. Google doesn't
street-view every paved road, but the majority of them are. They usually don't
street view gravel/dirt roads but there are exceptions such as the Dalton Hwy in AK. Sometimes Base Camp will not let you use a road no matter how you try to make it do so, it will run you to a certain point and then U-turn you back another way, this usually means an unpaved section.
I'm not sure that I have the correct road, but applying the Google Map Satellite view inspection technique to Hwy 1559 going north from the intersection of Hwy 221 in NC, I can see that it starts off as paved. From the satellite view I can see a painted center stripe going as far as the Blue Ridge Parkway exit, then none after that so I assume it is unpaved from there north until the intersection with Church Hollow Road.