arcgis 10.1 - Is there a way to improve the render quality of ESRI basemaps when exporting a map to PDF or JPG?

I've had this problem with ESRI base maps before but not this bad. The problem is that when I use an ESRI basemap as my backdrop, it looks fine in my MXD but when I export the map to PDF, JPG, or whatever format, the quality of the basemap in the export file is a lot worse than what I see on-screen in ArcGIS. Here's the most recent, egregious example:

What I see in ArcMap:

What it looks like in my exported PDF:

I've tried several things to solve this problem, and the result you see above is the best I can do:

• Turning up the export quality on the PDF to 600dpi or higher


• Exporting to JPG, or to TIF with no compression at all


• Clearing my cache on the basemap layers I'm using


• Printing to the Adobe PDF print driver rather than using Export to PDF

Some people apparently have this problem due to a slow internet connection, but since I can see the tiles in my MXD and they look fine, I don't think that's my problem.

Is there something I'm missing?