Created a custom list that manages a content type with some dozen columns.
Added it to a page and then via SPD, converted into a data view.
My Xpath expression was returning blank for a column named "Current Position". I referenced it thusly:
<xsl:for-each select="/dsQueryResponse/Rows/Row" >
The column in the CT is named "Current Status". It shows up in the lookup as "Current Status". Everywhere you look, you see "Current Status".
While thrashing madly about, looking for a solution, I instead referred to "@Recruiter" and behold! — that actually returned back the current status. I expected it to return back the recruiter when I did that.
I poked about in SPD. Go to that page in SPD and it shows the data view. You can inspect the actual data provided to the view and associated Xpath. Here I found out that indeed, the Xpath pointed at "Recruiter". Strangely enough, the "actual" recruiter field pointed from "Recruiter1".
SPD provides authoritative Xpath expressions for rows & columns in a data view.
Second, it shows the actual data. So for example, a column of type shows this: