Bug: Legend generated by ArcMap Server cuts off the first pixel column and the last pixel row
ArcMap server generates legends with one pixel row missing from the left and one line missing at the bottom. This may cause the legend symbolgy to appear awkward. For example, the bottom line of a polygon symbol may be missing.
This is only true for the last layer in the legend.
This is a known issue.
The swatchheight value can be reduced in the LEGEND request. This ensures that the symbology of the last layer in the legend is intact.