Hello, The following technical article explains basically what is happening: FAQ: Why do vector layers appear blurry when exported with a Bing map service? At 10.1, there is a Bing logo that is contractually required to be included with the map service by Microsoft. This logo draws on top of all layers in the map, which will cause all layers underneath (including text) to be rasterized. This will not happen at 10.0 because there is no Bing logo at 10.0. The other basemaps should be fine, unless there is a service layer that contains labels in it. An example of this would the "Imagery with Labels" basemap. If you use one of these and do not want the rasterizing to occur, turn off the service layer at the top which contains the labels. -Luke
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