Instead of looking at the workspacePath for sde layers, you can look at the database connection properties. That will give you useful, accurate information about the sde layers. For example:for lyr in arcpy.mapping.ListLayers(mxd):
if lyr.supports("SERVICEPROPERTIES"):
servProp = lyr.serviceProperties
print "Layer name:" + lyr.name
print "-----------------------------------------------------"
if lyr.serviceProperties["ServiceType"] == "SDE":
print "Service Type: " + servProp.get('ServiceType', 'N/A')
print " Database: " + servProp.get('Database', 'N/A')
print " Server: " + servProp.get('Server', 'N/A')
print " Service: " + servProp.get('Service', 'N/A')
print " Version: " + servProp.get('Version', 'N/A')
print " User name: " + servProp.get('UserName', 'N/A')
print " Authentication: " + servProp.get('AuthenticationMode', 'N/A')
print ""