People these days seem to confuse political stunts with grandstanding. Grandstanding, for the most part is what politicians do when other politicians complain of "political stunts," like pulling out an obscure (to Bill Frist) Senate rule to halt the Senate and force WMD's to be discussed. Grandstanding is "performing ostentatiously so as to impress an audience." That is, being Senator Joe Biden, who gives lengthy lectures to judicial nominees from his seat at the Judiciary Committee.
Political stunts, however, are guerilla tactics to get free media to a candidate or incumbent. For example, Democratic Candidate for the US House from North Carolina Larry Kissel copied another Democratic Candidate from Kentucky for the US House (whose name escapes me) by offering constituents gas at pre-incumbent prices to make a point that gasoline has become much more expensive since Congressman X went to DC...why isn't he doing anything about it? the gimmick attracted local news stories, and more importantly, potential voters to the candidates name and message, however briefly.
More recently, MO Secretary of State and US Senate Candidate Claire McCaskill bought 100 St. Louis Rams tickets so as to avoid a TV blackout for fans who can't afford said tickets. She then was able to get on local TV, giving away the tickets to charities for needy children or something. For $44,000, she got lots of favorable press coverage, more name ID, and appreciative Rams fans who might vote for her because of it.
Kissell's gambit also cost a couple thousand dollars, but it was well worth it, just Google his name and gas and see how many local news stories you see.
The key is, if done correctly, a candidate can get a dirt cheep positive issue ad out. One that sends a message that "I care about things that matter to you, and Congressman/Senator X doesn't."
Closer to home, Jim Matheson does this by donating his pay raise to charity. It is only a few thousand dollars each time, but it generates national coverage. Every year, some editorial board mentions his name about how more members of Congress should be like Jim and forgo their auto COLA. Every year, Jim gets to pick a needy charity who benefits from the money, and the coverage.
When ever people complain about political stunts, see if it is really grandstanding (to Biden). If so, join the chorus. But if it is truly a political stunt, you know they are just jealous they didn't come up with it first.