I think in 8 years and dozens of campgrounds I have only been guided a handful of times, ironically if memory serves me right they were actually campgrounds that were very easy to navigate it seemed that they were more interested in watching you pull/back-in for the protection of the utilities than actually helping you find the spot.
I learned a lesson early on (after some totally wrong directions at a KOA), now I get a map and ask them to mark not only the site but the outline the exact route through the campground to that site because I have fought that faded/no sign scenario too many times.
The suggestion to unhook and than search sounds good but not all campgrounds have room for you just to pull the MH over and leave it while you peruse the campground.
I have also asked for and received a discount when explaining that I would be arriving late and leaving early, in fact one time they said just leave what you think it's worth in the drop-box. I left 20 bucks and was thankful.
Again to the OP's question my suggestion is make them mark out the exact route before you leave the office, if they won't head on down the road.