There are other times, however, when someone's previous stance in a particular situation is at utter odds with their current position. Then such a vote can be instructive as to that person's current motivations...
Take for example Senator Bill Frist. Today he stands before America (running as hard as he can for the Republican nomination in '08) trying to take the "moral" highroad in the judicial filibuster issue. He claims that the judicial filibuster is unconstitutional. AND he claims that every judge the President nominated deserves their 'up or down vote'. Of course, that's not what Sen. Frist thought in 2000 when he voted for the filibuster of a Clinton appointee to the 9th Circuit.
Frist is clearly doing nothing but engaging in lowest-common-denominator partisan-ship with his nuclear option.
See this Center for American Progress story from January - Frist's Hypocritical and Dishonest Attack on Democracy. Exerpts:
Conservatives in Congress held up Paez's nomination for more than four years, culminating in an attempted filibuster on March 8, 2000. Bill Frist was among those who voted to filibuster Paez.
But American Progress has obtained a document that proves Frist was not, as he suggested, voting to filibuster Paez for scheduling purposes or to get more information. He voted to filibuster Paez for the very reason he said was illegitimate – to block Paez's nomination indefinitely.
Smith did not organize the filibuster to get more information on Paez (after all his nomination had been pending for four years). He organized the filibuster because he had already decided Paez was "out of the mainstream of political though and...should [not] be on the court[.]"