Answer
Using the GET_LAYOUT request in a custom client, you can access an ArcMap document layout.
There are cases in which the ArcMap layout exported from a ArcMap Service differs from expectations.
Such differences include:
1. The spatial extent of the data frame differs from expectations; that is, you are seeing more (or less) features than expected.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/22069' target='_blank'>Problem: The data frame extent is different than expected for a layout result from an ArcMap Server GET_LAYOUT request</a>
2. Map grids or graticules are misplaced.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/22551' target='_blank'>Problem: Grids or Graticules are incorrect in an ArcMap Server GET_LAYOUT request</a>
3. The scale bar width changes unexpectedly.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/23038' target='_blank'>Problem: Scale bar width for an ArcMap Server GET_LAYOUT request differs from expectations</a>
4. The GET_LAYOUT response includes only a portion of the layout; for example, the output displays only a corner of the original layout. This indicates that the ENVELOPE tag was used with PROPERTIES instead of DATAFRAME.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/22713' target='_blank'>How To: Use the ENVELOPE tag in a GET_LAYOUT request</a>
5. The overall image quality of the service layout is not as good as the original layout.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/22552' target='_blank'>Bug:DPI settings for GET_LAYOUT request for ArcMap Server is ignored</a> If outputing to a PDF.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/26649' target='_blank'>Problem: PDF output from an ArcMap Service GET_LAYOUT request has poor quality</a>
6. The image size is not as expected
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/22903' target='_blank'>Problem: The default image for an ArcMap Service Layout is too large</a> or
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/23911' target='_blank'>Problem: The output image of a GET_LAYOUT request is not the same size as specified in the request</a>